Aquarium plants Articles Caresheets

Marimo Moss Balls: Care & Info

Last Updated July 30, 2021
Marimo Moss Balls

Sharing is caring!

Aegagropila linnaei, better known as the marimo or moss ball, is a type of algae that grows into green fluffy balls under certain conditions. Marimo moss balls are a popular fish tank choice because of their low-maintenance care, interesting shapes, and ability to also be kept in a bowl or vase. 

Keep reading for everything you need to know about marimo moss ball care and starting your own marimo tank!

A proper environment

Marimos don’t have many care requirements when it comes to tank housing, but there are a few things to consider. First off, don’t keep your moss balls in a spot that gets a lot of sun. They naturally appear on the bottom of lakes where it’s quite dark, so they don’t react well to direct sunlight.

Another point to keep in mind is that, although some aquarium inhabitants, like shrimp and dwarf crayfish, love to forage on and hide behind marimo moss balls, there are also creatures that love it a bit too much and will attempt to eat or destroy it.

Plecos and goldfish usually don’t do well in a tank with marimo because both fish love to eat green algae. If you’re not sure if your fish or invertebrates will take an interest, just keep your marimo moss ball in a separate container to be safe.

An interesting note about the marimo moss ball is that it can actually be kept in a brackish water tank. It is noted on various aquarium plant websites that it is able to thrive in waters with a salinity up to mid-end brackish (that’s 1.015; check out the guest post I did for Sitting by the Koi Pond for more information on brackish aquariums). Adding some salt to the water is sometimes recommended when dealing with a marimo moss ball that is fading from green to brown.

Water changes

Whether you keep your marimo moss balls in a bowl by themselves or in a fish tank, it is always important to regularly change the water. While some aquarium keepers only do water changes every two weeks, some have found that their tank requires it every week; make sure to pay attention to the bioload entering your tank and how your cleanup crew and filter are handling the waste.

Change all the water in the bowl or around 25% in a filtered aquarium. Tap water usually works fine for this, although you might want to dechlorinate it if necessary.


A clean marimo is a healthy marimo! It’s a good idea to pick up your marimo moss ball once in a while (especially if dirt particles have accumulated on it or if the green has turned a bit brown or greyish) and gently wash it by squishing it a few times in a container with some clean water.

You can then roll it around in your hands to prevent it from falling apart from the squishing; this should be done very carefully. It helps the marimo moss ball maintain its nice round shape, which it would naturally get from being rolled across the lake floor by the current; this doesn’t happen in a bowl, vase, or aquarium on its own, so it’s a good idea to re-roll your moss every so often.

Cool water

In the “wild,” marimo moss balls only occur in cooler areas like Iceland and northern Japan. It prefers cooler water fish tanks; if its container/aquarium gets a bit hot (77Β° F/25Β° C degrees ) during summer, consider temporarily moving it to a slightly cooler place.

Your marimo moss ball can actually be placed in the refrigerator during the hotter months, but a spot near an air conditioner is also fine.

Sick marimo balls

Although marimo balls can withstand a range of temperatures and water conditions, they may turn a strange color; this is an indication that something is wrong.

Marimo turning white/lighter means that it is probably receiving too much light. If the marimo ball also seems a bit slimy or if its texture seems otherwise unusual, you may be dealing with hostile algae. These algae choke the slow-growing marimo, so it’s best to carefully wash them off or remove them with tweezers.

Marimo turning brown may be a sign that it’s time to gently clean it. If this doesn’t fix it, try carefully picking off the brown (dead) parts and adding a bit of salt to the water to stimulate growth. If the bottom of the marimo ball has turned brown because it hasn’t received light for longer periods of time, be sure to start rolling the marimo around a bit more often to prevent parts of it from dying off again.

Marimo turning black and/or falling apart. Marimo is unfortunately known to start decaying from the inside out, especially when it has been covered by hostile algae for a while or when it is simply too big for clean water to reach the inside. In order for your marimo moss ball to become healthy again, the black parts should be removed and the ball should be gently re-rolled. It’ll be smaller than it was before, but it now has a good chance of surviving and growing back.

Recognizing a fake marimo

Artificial marimos are a real thing. Most stores don’t mean to sell you the wrong thing, but sometimes there is some confusion. I’ve received a few comments asking about this, so here are some points to check if you’re not sure:

  • Artificial moss balls are usually made with a soft plastic ball covered in synthetic hair. The plastic can be quite obvious.
  • Most artificial moss balls are not kept in the plant tanks at aquarium stores. They are often sold pre-packaged or in the decorations section.
  • You can change the shape of a real marimo moss ball by rolling it between your hands. For example, if it’s lopsided, you should be able to roll it into a more perfect ball.
  • Real marimos can be picked apart (although I wouldn’t recommend this).
  • A fake marimo is often too perfect-looking. If your marimo has some bumps and looks imperfect, there’s a good chance it’s real.

Buying marimo moss balls

Although a marimo moss ball is not always easy to find in local aquarium stores, they are available online on many sites, like The Shrimp Farm or Amazon. Another option is to ask your aquarium store if they can order them for you, or buy them from another aquarist.


If you follow the guidelines from this care sheet, your marimo balls can live for years and years and eventually grow quite big or form multiple small marimos by falling apart. Don’t expect it to grow too quickly, though, marimos are said to only grow 5 mm a year!

If you have any more questions about marimo balls or want to share your own experiences with this interesting algae, don’t hesitate to leave a comment below!

Sharing is caring!

You Might Also Like


  • Reply Amanda K September 25, 2020 at 7:42 pm

    Hello! I have a 5 gallon tank with one betta and one marimo but I just purchased several more that are currently in quarantine. They have grainy stuff on them. The seller assured me it’s just sand but how would I tell if it was sand or some kind of larvae/eggs? I’ve tried searching but photos of Marimos that are infested with anything other than worms are hard to find! Thanks!

    • Reply Jennifer Doll September 26, 2020 at 2:36 am

      Hi Amanda!
      Since marimo balls can tolerate most conditions, I would just keep them in quarantine for 2-3 weeks to be extra safe (kudos to you for using that quarantine setup!). Any possible parasites will not be able to survive that long without a viable host. Any other hitchhikers that could possibly come in will also become apparent during that time and you will be able to treat from there.
      If you notice that the marimos start to brown or change color otherwise, try gently squeezing them out and rerolling them.
      I hope this helped and that it really is just sand!

  • Reply Shaikha June 24, 2020 at 5:04 pm

    Hello, Great article! .. I have a 15 gallon tank for my one betta fish and 11 marimo moss balls so far, planning to get more for aquascaping! Also thinking about getting a snail or two. I have one question. I have an IAL extract and a vitamin complex that I’m planning to use on a regular basis for my betta. Will the IAL extract and the vitamin extract harm my moss balls? I really love them and planning to keep them since I’m not planning to get real life plants.

    • Reply Jennifer Doll June 24, 2020 at 11:15 pm

      Hi Shaikha!
      Thank you for reading! The IAL extract will not affect your marimos or betta in any negative way, as long as it is dosed in moderation; keep in mind that marimos are very resilient on their own and can tolerate a lot! The only way you could potentially hurt the things in your tank is by decreasing the pH too much as a result of dosing too much IAL extract. But even then, I think it’s pretty hard to do.
      As for the vitamin complex, it’s a little harder to tell without knowing what the exact ingredients are. If you have a link/list, I would be more than happy to take a look.
      Also, may I ask what you’re dosing vitamins for? The IAL extract will boost the immunity of your betta by itself. And as long as your fish isn’t recovering from any diseases/illnesses, I think the vitamins might be a little overkill. Your money might be better spent on providing a varied and high-quality diet, but that is for you to consider.
      I hoped this helped! And please send that list if you are still considering vitamins.

      • Reply Shaikha June 25, 2020 at 2:49 am

        Thanks for replying! Well, When I first got my HM betta, it got a fin rot, treated him with medication, got better but as soon as I stopped the medication, he became worse. The buyer took him back to treat him by himself and I thought its a great opportunity to upgrade his tank from 9 gallon to 15, replacing my plastic plants with silk ones and adding lots of marimo moss balls since I’ll aquascape. as I said maybe adding a snail or two. I felt guilty to be honest, no one told me about recycling the tank .. etc, etc.. Did all the research by myself and now I’m just waiting to start aquascaping and getting him back to his better home (hopefully). I love IAL but I think I’d like to enjoy having my fish back in clear water for now. I saw a breeder using this vitamin complex and I got it from him since I won’t always use the IAL extract and even when I will, I won’t use a lot. Took pics of the vitamin complex and the IAL extract that I will use.
        “Sorry I don’t know how to rotate the images, I’m new lol”
        One more question, Will nitrite snails eat and destroy the moss balls?

        • Reply Jennifer Doll June 26, 2020 at 5:19 pm

          The upgrade sounds great! And will definitely be appreciated by your betta. It can be a frustrating (and expensive) hobby, but it’s definitely worth it in the end. I understand not wanting to stain your water and thank you for sending the pictures. I can’t seem to find that brand online, so it is a little hard to see how the ingredients will directly help your fish. I don’t see how it could hurt your fish as long as you dose appropriately. I would also make sure to check the ingredients of the food that you plan on using so that you don’t overdose on one specific vitamin (if the food contains supplemental vitamins). Once your fish seems healthy and settled in its new tank after several months, I would maybe suggest getting a food that will provide those vitamins instead of having to dose this product.
          Nerite snails are pretty much 100% safe to keep with plants, so your marimo balls will be just fine even as algae :-). The only time you might see them munching on plants is if they’re dead/decaying; the babies also like to hide together in the plants, too.

          • Shaikha June 27, 2020 at 9:44 am

            Thank you! After watching a lot of blackwater videos, I started to like it! so maybe I’ll stick with IAL. I’m not planning to get any snail babies lol. I’ve read that nerite snails dont reproduce in freshwater? I’m planning to feed my HM Betta omega one frozen bloodworms twice a week and Omega one betta pellets twice a day. I don’t know what to feed my snail when I get it, thinking about the bottom feeder wafer? But I’m also thinking now, what to do if my moss balls started turning brown while they’re glued on the stones lol. “Don’t have aquarium salt where I live but I’ll order it online if I have to like what I did to most of the stuff I needed for the new tank.

          • Jennifer Doll June 27, 2020 at 5:07 pm

            Yeah! I personally really like the effect that IAL gives. And with extract, it’ll be easier to gauge the coloring if it’s still a concern. That sounds like a good feeding routine, just don’t overfeed the pellets; maybe offer 1-2 with each feeding. Bettas have a tendency to become overweight!
            And yes, you are correct that juvenile nerites need brackish water in order to grow/survive. Just make sure that you’re definitely getting nerites (there are a lot of snail species out there) and you should be fine. I usually give my snails an algae wafer once or twice a week. As long as it’s not left to rot, then you shouldn’t have any problems. You can also feed them blanched vegetables for a treat.
            If possible, I would suggest unsticking the marimo balls. Browning can be the result of getting too much light (which is probably not the case, but always possible). More likely because they’re stuck, the browning is caused by them not being turned/rolled. It is good to turn them in the tank ~once a week and then occasionally squeeze them out/reroll them maybe once every month. If your filter is strong enough, you can also put them under that flow and they might naturally bounce a little on their own.
            Aquarium salt is good to have in many cases. If your area is prone to power outages, a battery-operated air stone is definitely recommended, too. It can save your tank for at least a couple of days without power. Everything else is pretty straightforward: heater, light, fish net, food, water conditioner, filter/filter media.

          • Shaikha June 28, 2020 at 5:34 am

            Thank you so much for all these information! I have everything so far, (tank, filter that comes with the tank, water conditioner, bacteria enhancer, heater, thermometer, ammonia alert + test strips). So you’re suggesting to not stick the moss balls with glue when I split them apart on the stones? So I can take them out and clean them? Will anything I’ll feed my snails affect my betta, like the wafer and the vegetables?

          • Jennifer Doll June 28, 2020 at 9:12 pm

            It’s no problem πŸ™‚ even I learn new things about this hobby every day. Test strips are a little untrustworthy/inaccurate. I would switch to real liquid reagent test kits if you have the means. You will get more exact numbers, making finding a problem that much easier.
            Correct. Marimo moss balls occur naturally on the bottom of lakes where the currents roll them around to maintain their shape/health. Every week or so, you can use a fish net to just move it around a bit. Then every 4-6 weeks, you can actually take the marimo ball out and gently squeeze it in some of your aquarium water to get some of the waste off, and then reroll it. This might sound a lot more complicated than it actually is, but it’s just to keep your marimo from sitting on one side for too long!
            As long as the vegetables are thoroughly cleaned under some water, you shouldn’t have any problems (make sure to dry off as much of the water as possible to prevent unwanted nutrients from entering your system). I would suggest removing the vegetables after a day to prevent them from rotting. Your betta will probably even pick at the wafers and possibly the vegetables!

          • Shaikha June 29, 2020 at 1:45 am

            That’s awesome! Thank you a lot.. really helped! For the marimo moss balls, I’m doing that at the moment, making sure they’re all clean and healthy before getting in the tank, putting them in the fridge every other day or so. And yes I will consider the liquid test kit beside the ammonia alert! Again. Thank you so much. Finally an awesome and friendly website!

          • Jennifer Doll June 29, 2020 at 7:22 pm

            Happy to help :-)! Please feel free to ask any questions you might have in the future.
            Though, I am a little confused about what you mean by putting the marimos in the fridge? The changes in temperature could be causing them to brown, too, and I don’t see any reason to put them in the fridge at all. Unless I’m reading it wrong and you mean putting vegetables in the fridge!

          • Shaikha July 8, 2020 at 8:39 pm

            Haha! I heard since putting marimo moss balls (prefer cold water) to a betta fish tank (tropical warm water) might turn the marimo moss balls brown a little bit, so once in a while its better to put them in the refrigerator for 24 hours will help to keep them fresh and healthy. please correct me if I was wrong or if you have another way.

          • Jennifer Doll July 9, 2020 at 12:29 am

            Ah, I understand! Though, honestly, the refrigerator method is probably doing more bad than good. Sudden temperature changes will also cause your marimo (and most aquatic things) to stress out. You are right that marimos prefer cooler water though! However, they seem to adjust fine to temperatures up to about 80Β° F (26.7Β° C). If you’re really worried about temperature, you can start slowly adjusting your heater thermostat to 78Β° F (25.6Β° C) over a week; no lower than this though as it may start to affect your betta.
            Marimos are pretty resilient. And sometimes it’s better to have a stable tank than to chase numbers for ‘perfect’ parameters.
            In short, see what works best for your marimo and your betta, and don’t worry too much!!

          • Shaikha July 9, 2020 at 6:01 pm

            Got it! Thank you so much! I do worry too much that’s my problem haha.. I appreciate it a lot. Thank you again!! πŸ™‚

          • Jennifer Doll July 9, 2020 at 11:55 pm

            No problem :-)! Keep us updated on how things go.

  • Reply Stacey May 13, 2020 at 4:00 pm

    My marimo is growing a tail. It started out as just a few feathery streamers sticking out on one side, but now it’s starting to look like a bunny tail poof sticking off the main tribble. I keep it in a 10 gal aquarium where it gets to bounce around most of the day in the bubble stream over the air stone. The tank is by a window that gets direct light, but only in the morning, and so far the marimo has remained green, anyway. The tank is well planted, so I guess the marimo gets enough shade. I’m wondering why it’s sprouting feathers like this. I don’t mind, it’s actually kind of cute, I just want to make sure there isn’t a problem. Is it budding? Is it falling apart? Is something in my tank pulling tufts out of it? I added some minerals to the water several months ago for my plants and snails and things, and I did notice that some of my floating plants really took off afterwards. Could that have anything to do with it? I think I added calcium, magnesium and iron. I have ghost shrimp, nerites, a mystery snail, tiny pond snails, some random tadpoles I found, and a handful of baby pumpkinseed sunfish, though I think the tail started growing before I added the sunfish. Any thoughts? Any suggestions will be appreciated. Thanks

    • Reply Jennifer Doll May 13, 2020 at 10:26 pm

      Hi Stacey,
      Thanks for all the details! It really helps.
      Honestly, if it’s still green and nothing else in your tank looks like it’s struggling, I would leave it alone. I see that it is in a spot where it regularly gets moved around. One thought could be that it’s starting to lose its shape. Which if this continues, then I would maybe take it out and reroll it.
      My other thought is that it could be growing, but marimo moss ball growth rate is typically very slow and I doubt that these tufts would just appear overnight. But maybe it just really liked what you’ve been supplementing!
      I’ll leave you with this.. “If it’s not broken, don’t fix it.”
      Let us know how it goes! Good luck!

      • Reply Stacey May 26, 2020 at 3:16 pm

        The tail is continuing to grow. I would say it’s grown several milimeters since I last posted a little over a week ago. It sprouts from the ball at a single point, but then fans out into a feathery poof that is about 1.5 centimeters long and 2 centimeters wide, though much looser than the main ball itself. The tail only started growing about a month ago. I had no idea any part of a marimo could grow so fast. I can’t tell if the rest of the marimo has grown much since I got it about about two months ago. Since I last posted, I have also added a bit of phosphate to the water. Just in case anyone is curious about my water setup, I used 1/2 distilled water, 1/2 very hard tap water, maybe 6 600mg spring valley calcium citrate tablets, 6 65mg spring valley iron tablets, 6 doublewood 1500mg magnesium malate capsules, 2 spring valley 99mg potassium tablets, and 3ccs fleet enema (phosphate) per 10 gallon tank. Plus, the fish no doubt provide plenty of nitrogen. I use test strips once in a while to make sure the ammonia isn’t too high, and since the nitrogen looks good, I assume the microflora that turns the ammonia into nitrogen must be fairly healthy. All the supplements I used dissolve in water without needing to crush them.

        • Reply Jennifer Doll May 28, 2020 at 11:04 pm

          I honestly just think that it sounds like your tank is thriving! Who knows… maybe it will go through this growth spurt and then not grow again for the next few years! These little ecosystems can definitely be strange.
          Again, if you want a more uniform look, then I would maybe consider rolling it more tightly. But I would probably just leave it alone until it starts causing problems.

        • Reply Stacey June 1, 2020 at 7:03 am

          Up to 3 cm now. I tried rolling him, but the little tail just poofs back out. Guess it’s time to name it before it sprouts legs and crawls out of the tank. Finally took a pic:
[email protected]/49958096428/in/dateposted-public/

          • Jennifer Doll June 2, 2020 at 12:07 am

            Woah! That’s definitely not what I was expecting at all. I can see why you say it might just get up and leave..
            I have a couple of theories, so just hear me out. How long have you had this marimo?
            Fake marimo balls are kind of common to across. Now there are a few ways that they could be fake: 1) pieces of the algae are glued together and there will be a hard center 2) pieces of the algae are glued onto a styrofoam ball 3) another species is glued on top of the styrofoam ball entirely, like Java moss. Yours looks like a real marimo, but I’m wondering if some other kind of algae/plant got mixed into the ball at some point; what’s weird is that the tuft seems to look exactly like the rest of the ball, though.
            This could maybe even be due to another pest algae taking hold on that specific part of the ball. Is that tuft usually on the top that faces the light? Do you or have you ever had an algae problem in the tank?
            I’m honestly at a loss! I think it could still possibly just be new growth that is having a bad hair day. But after researching a little more about the possibility of pest algae, I also slightly think it could be that depending on how long you’ve had it and the other logistics.
            If you’re ever concerned, it is easy to propagate them as you just gently cut them up and then reroll them.
            Let me know more about the tank though and what you think!!

          • Jennifer Doll July 21, 2020 at 7:02 pm

            Hey Stacey! Any updates?

  • Reply Magennis February 24, 2020 at 7:30 pm

    Great article! Can the marimos be too crowded? I have about five in a tall vertical jar, and I wonder if I’m cramming one too many and should separate them.

    • Reply Jennifer Doll February 28, 2020 at 6:34 pm

      Hi Magennis,
      While you can’t have too many marimos, it’s important to make sure that they’re all getting the lighting and nutrients that they need to continue growing and being happy. If they are in a tall jar, make sure that they aren’t blocking each other out for light. As they continue to grow, also make sure that you can keep up with their increased nutrient uptake.
      Happy plant-keeping!

    • Reply Elijah May 3, 2020 at 4:44 pm

      Hello! I have a single ball, I have him in a simple jar, I was wondering if the lid should stay off or not, as I’m not very well aquainted with marine life.

      • Reply Jennifer Doll May 6, 2020 at 12:38 am

        Hi Elijah!
        Marimo moss balls do well in just about any tank, so I don’t see any immediate reason why you would need the top off all the time. That would just lead to quicker evaporation in the long run. I do think that you should regularly do water changes still, and that would help re-oxygenate the water. At that point, you could also rotate/reroll the ball if needed. So to answer your question: lid on!
        Good luck!

  • Reply Bee September 4, 2019 at 11:29 pm

    We kept a Marino in our fish tank until it started disaggregating.. we’re not sure what happened. We got rid of it a while ago but started having tons of marino’s filaments growing in the tank since. It looks awful and so difficult to remove as it sticks to the other plants.. not sure what to do beside removing by hand every months.. any suggestion? Thanks!

    • Reply Mari September 5, 2019 at 11:13 am

      Yikes! Yeah, Cladophora algae can be very challenging to remove if it really is that. Manual removal really is the recommended way to go here since adjusting other parameters barely has any effect. You can also spot dose with something like Easy Carbo to nuke specific patches. Good luck, hope it works out!

      • Reply Bee September 5, 2019 at 7:47 pm

        Thx Mari!
        You made me realized that the filaments were not pieces of my Marino ball..! I found out by searching Cladophora that mine were probably Green thread algae.. Are Amano shrimps really a good solution?

        • Reply Mari September 6, 2019 at 12:46 pm

          You know, I was thinking maybe that would be it since the Cladophora strings don’t look very Marimo-y. Well, green thread algae are a bit easier to get rid of luckily! The tips from my article on hair algae apply to it. What did it for me was removing one of the lights from my tank: the previous owner had installed very powerful lighting because he ran a Co2 system as well, but without added Co2 it was just too much and caused an imbalance. Amano shrimp do assist, as do algae eating snails like Nerites, but obviously in the end you’re going to want to resolve the underlying problem.

          Good luck!

  • Reply Ann May 3, 2019 at 11:58 am

    My two were very healthy until they accidentally got hit with direct sunshine at the babysitter’s house. They then had brown spots. Since then they’ve never fully recovered and are slimy to the touch. I change their water once a week with chlorine-free water. A white film is sometimes floating in the water.

    What can I do to make them happy again? I’ve had them for around five years.

    • Reply Mari May 3, 2019 at 1:05 pm

      Yikes, sorry to heasr that! It sounds like you’re doing everything right, though. You could consider picking off the nasty bits with a pair of tweezers to give the rest of the ball a chance to recover.

      Hope they improve! Good luck πŸ™‚

  • Reply Jonathan April 7, 2019 at 11:55 am

    Hello! Wonderful article you’ve written! I’m hoping to buy my own Marimo ball someday soon! I’m worried about getting a fake, so I want to be sure my first marimo is the real thing. I do have two questions before getting my own.
    Through my reading I’ve found that they love the cold, and seeing as it can get a bit toasty here in the midwest, I was wondering if I could put ice cubes (that are dechlorinated) in the water? I understand you can put them in the fridge for short periods of time to cool them off, but I was curious if dropping a few ice cubes would be an easy fix.
    My second questions comes from a few pictures I’ve seen. Some people store them in sealed containers, for aesthetic reasons I’m sure, but is that actually good for the plant?
    Thank you so much for your help! I feel like I’m on my way to giving my future marimo an ideal home!

    • Reply Mari April 8, 2019 at 1:13 pm


      Glad you found the article helpful! To answer your questions, first off, I personally wouldn’t do ice cubes since it just doesn’t really work in the long term. I’d just try to keep the Marimo in the coolest room you have – if you have any air conditioned rooms they’ll be fine, the real problem is when the Marimo is in an aquarium heated to a high temperature like a Betta tank.

      The sealed containers aren’t really ideal, no. Same issue with houseplants in sealed terrariums – there is no oxygen exchange. It’s a little better if you change the water very regularly I’d suppose, but ideally you’d just go for an open top container.

      All in all, as the article says, Marimos are really quite easy to keep alive and thriving. Don’t worry about things too much, you’ll be fine! πŸ™‚

  • Reply Shantel March 29, 2019 at 12:20 am

    We have two Marimo. I took them out to clean them. I rinsed them off with the tank water. One if then won’t go back as a ball. Also are they supposed to float of just sit in the bottom of the tank?

    • Reply Mari March 29, 2019 at 2:16 pm


      Sorry to hear your Marimo appears to be falling apart, but it’s nothing to worry about luckily. Just keep gently re-rolling it regularly and it will likely eventually go back to its original shape. Marimos can both float and sink – they’ll often float after being washed, and then sink once all the air has been released from the inside. πŸ™‚

      • Reply Tee March 31, 2019 at 6:17 pm

        I just purchased two huge gorgeous Marimos but they have snails what can I do to get rid of the snails without hurting the moss balls I haven’t added them to the tank yet they are still in the cup So they are quarantined.

        • Reply Mari March 31, 2019 at 6:54 pm

          Hi! An easy way to get rid of snails that generally doesn’t hurt plants too much is to do a bleach dip with 10 parts water and 1 part bleach. It’s what’s generally done in the quarantine phase to get rid of any nasties.

          Good luck! πŸ™‚

  • Reply Eve Rosin March 8, 2019 at 3:24 am

    Hello, I have had the same Marimo for 5 years now. My dog recently removed it from the glass container it was in and shredded it up quite a bit. Do you know if it is possible for me to try and roll it back together over time and if it will survive what my dog did to it?

    • Reply Mari March 11, 2019 at 4:37 pm

      Awww, so sorry to hear your Marimo got wounded haha! But yes, you can try rolling it back together and it should survive. Remember, a Marimo doesn’t have to be round – that’s only one of the shapes Cladophora algae can take. So even if it’s ugly for a while, it’ll live πŸ™‚

  • Reply AnnaMaria January 25, 2019 at 12:13 am

    Hey me and my friend are trying to get some of these and were wondering if this was a trustable source to buy them from…. Also was wondering how we would be able to tell if they are fake or not if we buy very young ones. I hope for a response! Thanks, Anna

    • Reply Mari January 29, 2019 at 4:29 pm

      Looks just fine to me. Do keep in mind that you can get them much cheaper than over there and just set up a pretty vase yourself with some dollar store items. Though that all depends on your personal preference! πŸ™‚

  • Reply Kentaureus September 6, 2018 at 2:35 pm

    is this too much light for marimo? i have direct sunlight about two hours, mostly it is indirect

    • Reply Mari September 6, 2018 at 4:32 pm

      That looks fine to me actually! If you notice any algae growth you can move it to a spot with less direct sunlight but I don’t think you’ll have any issues.

      • Reply Kentaureus September 16, 2018 at 2:03 pm

        Hi, thanks! – still little bit scared/confused – when i have my marimo there, where the sun is shining for about two hours and mostly indirect light – it create air bubbless, but i think there is something wrong – he marimo has whitish aura around it, like the very outter shell is whitening – and when i put it into more shade, it stop creating air bubbles… so confused

        • Reply Mari September 21, 2018 at 5:35 pm

          Hey, sorry about the late reply! I’d personally leave it in an area that’s neither shaded nor sunny – maybe a little further away from the window? The outer bits whitening can be a sign of too much light.

  • Reply Alex Bustos August 20, 2018 at 4:54 am

    Hello! I have been super into Marimo for a while and I finally decided to get my first Marimo. I want to provide as much careful planning and love as any pet deserves so even though I have read that Marimo can strive in pretty much any tank I would like to provide the best housing possible for it, like a tank that can keep the water colder for longer and maybe even a filtration system to help Marimo dance and roll around easier. Would a BiOrb provide a suitable housing for Marimo or what would you recommend for an ideal housing scenario? I would be keeping Marimo by itself but if it’s more beneficial to have some sort of companion I would love to hear about it. Thank you in advance!

    • Reply Mari August 21, 2018 at 10:47 am

      Hi! I think a BiOrb would work well for one or multiple Marimo balls – it doesn’t matter how many you have but I’d imagine that it looks more decorative if you have more. If you get a large enough biOrb (> 5 gallons) and do some research into their care you could even keep some cherry shrimp in there. They don’t mind the cooler water and will help keep the tank clean. There’s a caresheet here if you’re interested.

      Sounds like a cool set-up! Good luck πŸ™‚

  • Reply Lubos August 19, 2018 at 10:43 am

    Hi, i have a bit problem with marimo and dont know what to do? it has whitish aura around it – algae on outside is turning a bit white, it is definitely not paraziting algae – it is marimo but turning white – i moved it too more shadish place but i am not sure it is helping:(

    PS – i already posted comment – didnt showed so i am hoping it isnt some anticomment spam, so i am not sending it twice:D

    • Reply Mari August 19, 2018 at 10:50 am

      Both your comments posted πŸ™‚ what is the temperature of your Marimo’s water? They can definitely suffer a little if they’re too toasty.

      • Reply Lubos August 20, 2018 at 1:55 pm

        hi, about 15-20 C – it is in my room, and i have temperature 21 C

        it looked like this 1 pic,, now it is more greenish pic 2- so i think the problem was aquarium and light – or i hope… stll hoping that whitish parts will vanish completely – you can see it a bit on that tuff of algae

        • Reply Mari August 21, 2018 at 10:43 am

          It might have been a little hotter in the tank where the Marimo was by the window. It can heat up quickly! So I think everything should be alright now, just continue to care for it as usual πŸ™‚ the white might not disappear but you can always carefully trim it off yourself.

          Good luck!

  • Reply Britt July 14, 2018 at 2:03 pm

    Hi I was gifted a Marimo Ball about a year ago. We just went through a heat wave and my marimo is brown. We have no AC in the house and I didnt change the water in his bowl during because I am stupid. I checked the inside and its green. I dont know what to do. I keep reading to pick off the brown but there is not brown spot…. its just all brown with a green core. I cleaned the water and I tried rolling it back into a ball but the crack I made to check… is still there. Also I am noticing little white particles within my Marimo. They are like…. salt rocks… not squishy. Im not sure if I should pick these off? Please help. I am nearly in tears. My Marimo is named Levi and I dont want him to die πŸ™

    • Reply Mari July 14, 2018 at 2:32 pm


      So sorry to hear Levi isn’t doing too well at the moment. The brown bits are dead and won’t be coming back, so the only thing you can try at this point is try to ‘free’ the green parts before they die off too and try to re-roll those. I realize most of the Marimo will be gone this way but unfortunately it’s your only option.

      Good luck and I hope you can work it out.

  • Reply Marimo Balllllll April 16, 2018 at 2:02 am

    I just got 3 Marimo Moss balls and I tried uploading earlier but i think it wasn’t accepted because it had a link to a picture, anyway I have 2 questions, 1. Is it normal that the water is bubbly against the glass? The water isn’t all bubbly but it’s just bubbly on the outside. And 2. Is it okay that my Marimos are a darker green instead of a lighter green? I haven’t heard of any dark greens.

    • Reply Mari April 16, 2018 at 11:46 am

      Hey, your previous post did go through but I have to approve everything manually to prevent spam. It looks normal to me – did you just fill up the bowl? Bubbles like that form after water changes and such. The Marimos also look pretty normal to me, so I don’t think you have anything to worry about! Just follow the guidelines in this post and everything should be fine.

      Good luck! πŸ™‚

  • Reply LR April 16, 2018 at 1:07 am

    I just 3 Marimo Moss Balls and I already have a few questions. 1. What does it mean when the water becomes bubbly against the tank? And 2. Is it okay for the Marimos to be a kinda dark green? Here’s a picture of them:

  • Reply Angie February 17, 2018 at 1:51 am

    I just got a Marimo ball and it says to propagate it I can cut it in 4 o\pieces and wrap each piece with thread. Can I actually sew them together?

    • Reply Mari February 17, 2018 at 6:52 pm

      I guess you could!

  • Reply Mercedes January 25, 2018 at 3:45 pm

    Hello, I just purchased a Marimo moss ball and while I was rinsing it I noticed tiny white spots that seem to be attached to the ball….any idea on what these can be? They aren’t perfectly oval like snail or shrimp eggs might be. Just want to be sure it’s nothing bad before I put it in my aquarium with my cory cats. Thanks!

    • Reply Mari January 25, 2018 at 5:54 pm

      Oh dear, stuff like that can be so difficult to figure out. Could it be nerite snail eggs? If not, I would maybe just do a bleach dip to kill it if it happens to be alive and then it should be safe to put the moss ball in the tank. A bleach dip is just something like 8 parts water and 1 part bleach. Your marimo won’t be happy about it but it shouldn’t be too harmful! πŸ™‚

      • Reply Mercedes January 26, 2018 at 12:17 am

        Thanks! I know, I’ve had such a hard time trying to ID what this could be. I’ve read mixed reviews about bleach and peroxide dips for the moss balls because they are just algae. Someone suggested tucking it in the fridge for 24 hours to help kill off anything that might be on it so I’ve done that and a bunch of rinses. I guess depending on how paranoid I feel after two weeks of it sitting out on it’s own I might try the bleach dip. I JUST got my tank cycled and fish all happy so I would hate to disturb them!

  • Reply Bob March 1, 2017 at 6:45 am

    I’m travelling from the US to Japan soon and would like to take my marimo with me if I can (preferably in the flight with me so that they aren’t stuck in my suitcase), but I can’t find information about whether or not I can bring them anywhere. I know there are often rules against whether or not you can bring plants with you and was wondering if anyone has had experience with this or knew where I should look to find out? Thanks in advance~!

    • Reply Mari March 2, 2017 at 6:37 pm

      Hope someone can help you! I know rules are often very strict, although here in The Netherlands I think there exceptions if you take it with you on the flight instead of putting it in your suitcase.

  • Reply WTDominator987 February 16, 2017 at 10:24 pm

    oh and this is my first one i ever had. Thanks

  • Reply WTDominator987 February 16, 2017 at 10:20 pm

    Hello I just bought a marimo from petsmart and i will need some help.Its still in its container it was in in petsmart. Any help will be fine and appreciated

    • Reply Mari February 19, 2017 at 11:29 am

      Hi! Did you read the article? It contains pretty much everything you need to know about Marimo care. If you have any additional questions feel free to ask!

  • Reply Leng February 10, 2017 at 6:50 am

    Hi Mari, i have stumble your webby by chance since i’m searching for more info on marimo..
    I loved marimo and have purchased quite a few within these few months. However, some of my marimo have turn brown and it has this decaying smell which stink badly.. I’m wondering whats happening and how do i savage the situation ? Any advice will be deeply appreciate πŸ™‚

    • Reply Mari February 10, 2017 at 10:30 am

      That’s unfortunate, sorry you haven’t been having too much succes with them so far! Are you keeping them in an aquarium or in a vase/other container? I haven’t heard of this happening in an environment with clean water so if you’re keeping it clean it’s odd that this is happening. I’m not sure whether the marimos can still be saved – I would recommend removing all the dead, brown parts and checking if there is still green inside.

      • Reply Leng February 21, 2017 at 8:12 am

        Hi Mari,

        I’m keeping the marimo in an aquarium tank with fishes. Hmm, i suspected it could also be the lighting that accidentally turning marimo into brown & eventually stink badly. The fishes faeces does not help too. I will be removing all the dead, brown parts and thank you for your reply πŸ™‚

  • Reply Nat January 13, 2017 at 9:01 pm

    I’m wanting to set up a plant-only tank (I just lost a betta and need time to recover before I try fish again), and already have a couple marimo. Are there any other plants I could put in with them that would do well in the same conditions?
    I have an unheated 2.2 gal tank with a bubbling airstone filter and LED light. Will this light be enough for the marimo? Or other low-light plants? Thanks!

    • Reply Mari January 13, 2017 at 9:13 pm

      I can’t tell you much about whether the LED will be enough, that depends on a few other factors like the amount of lumens it produces. The amount of daylight it receives also influences plant growth.

      In any case, you could try Java moss or maybe a very small plant like Anubias nana to accompany your Marimo. Good luck and sorry to hear about your Betta.

  • Reply Sami January 4, 2017 at 6:08 pm

    I have a small Marimo about 1 cm and I accidentally split it the spilt is not so big but when I try to roll it it keeps on opening should I split it? Or will it hurt the Marimo since its small? The marimo has no other problems it’s healthy and green in colour.

    • Reply Mari January 7, 2017 at 4:05 pm

      I don’t think it matters too much. You could leave it as is or split it if you don’t like the current look. It won’t suffer either way. πŸ™‚

      • Reply Amanda May 8, 2019 at 4:23 pm

        Hello, thanks for the great article. I just got some Marino balls and want to keep them happy. I have a few questions.
        1. Do they generally remain clean and not build algae if I clean it fortnightly and have the lighting right?
        2. I want to add one to a fish tank. What fish or shrimps are not going to eat it?
        3. Do I need to feed them any nutrients or so they live pretty independently?

        • Reply Mari May 8, 2019 at 4:37 pm


          Yes, your Marimos should stay free of algae like that. Shrimp will never eat it, when it comes to fish you need to be avoiding the herbivores. Anything that’s labeled algae eater should be out, and since you should research a fish before you buy it anyway that gives you a good moment to look at what it likes to eat.

          Your Marimos will appreciate a little bit of fertilizer every now and then but I’ve found that they do fine on whatever is in my tap water as well. You could always add in some aquarium water if you want to give your Marimos something extra since they love the fish poop that’s in there, haha!

          Best of luck, hope they grow and thrive πŸ™‚

  • Reply Vivace December 10, 2016 at 5:13 pm

    Hi due to some reason i open up my marimo to check on the inner condition in July. Now they are growing okay but they seems to be growing separately. Is there any chance for them to grow back into a ball? Do you mind me to send you the photo of my marimo so that you can try to help to evaluate the condition? Thanks.

    • Reply Mari December 10, 2016 at 5:38 pm

      I think it’s best to leave them separate, getting them back into a ball is probably pretty difficult. Just roll the two separate pieces regularly so they grow nice and round and things should turn out fine. Good luck!

  • Reply huiweneng September 23, 2016 at 12:29 pm

    I did not change the marimo’s water for around a month because of some personal reason . When i back home i found that my marimo turned a little bit black on its surface i immediately change the water and clean the surface but it doesn’t work may i know what should i do to save my marimo?
    Thanks for reply πŸ™‚

    • Reply Mari September 25, 2016 at 1:56 pm

      Try removing the black bits, those are dead and won’t disappear by themselves. After this the marimo should be fine πŸ™‚

  • Reply sarah September 9, 2016 at 12:54 pm

    I’m going to set up a brackish tank and want to put some marimos in it. Can a just throw them in, or should I acclimate them?

    • Reply Mari September 10, 2016 at 4:16 pm

      You can just throw them in. They adapt very easily to different water conditions and such.

  • Reply Trissa August 12, 2016 at 5:28 pm

    Hi, I’m about to travel to another place and it’s gonna be a long flight πŸ™ I wanna bring my marimo with me but then I’m afraid that if I pack it within one of my luggage for that amount of time (about a day), it won’t be able to receive lights, nor oxygen. Is there any other option available?

    • Reply Mari August 13, 2016 at 1:41 pm

      Hi! When they’re being shipped marimo balls don’t receive any light either. If you’re not allowed to take any fluids on the plane just pack yours in a plastic baggy with moist pieces of cotton ball so it doesn’t dry out. Just put it in a vase of water as soon as you arrive at your destination and it should be fine πŸ™‚

  • Reply Trixie Coley July 1, 2016 at 6:04 am

    Hello! In order to see real results with removal of nitrates and ammonia, how many marimos per gallon would be appropriate? I have a small 3 gallon with a single betta. Is there such a thing as having too many marimos?

    • Reply Mari July 2, 2016 at 12:57 pm

      Hi! Unfortunately, Marimo balls aren’t suitable to rely on for the removal of nitrates and especially not for the removal of ammonia. Your tank should be filtered and cycled for that! Having a few marimo balls in there could lower the nitrates a bit, but you still have to do regular water changes. A properly heated betta tank is also a bit hot for marimo so I would keep a close eye on them to prevent any rot. You can’t really have too many, but 3 gallons is very tiny (too small for a betta in my opinion) so I would be careful not to limit the swimming space even more.

      Good luck!

      • Reply Trixie Coley July 2, 2016 at 8:15 pm

        I didn’t mention that it is a filtered and heated tank, temp stays around 76. So I wouldn’t necessarily be depending on them for nitrate removal, I just thought it would be a nice perk. πŸ™‚ And I really dislike gravel so I was thinking of putting some balls in the bottom in lieu of gravel. Or maybe a much thinner layer of gravel. So his swim space wouldn’t be affected very much. Thanks so much for your advice! I love your page. Super helpful!

  • Reply Eddie June 24, 2016 at 6:09 am

    Hi I just put a Marimo Moss ball inside my tank with an african Cichlid and when I came back from work he seemed to have pulled it apart πŸ™ there’s still a big chunk he left but it isn’t shaped as a ball anymore, is it dead? or can it survive?

    • Reply Mari June 26, 2016 at 9:10 pm

      Sorry to hear that! You can re-roll any bigger bits. Just keep giving them a gentle roll regularly and they should probably recover πŸ™‚

  • Reply Bre June 1, 2016 at 6:50 pm

    I just got some moss ball and they were dark green and smelly. I washed them a couple of times before putting it in the tank. They are now making my tank green. Is that suppose to happen?

    • Reply Mari June 3, 2016 at 10:48 am

      I’ve never heard of that happening! You might want to take them out of your tank and see if you can revive them in something like a vase to prevent endangering your fish with bad water quality.

  • Reply Alaina May 22, 2016 at 1:38 am

    Hi, I came home and found my mom had taken my marimo ball out of its water and it dried up. I put it back in but it’s been a long time, is it truly dead? Thanks

    • Reply Mari May 22, 2016 at 2:07 pm

      Hmm, I’m afraid it might be a goner, yes πŸ™ You could try picking off the dead bits to see if there’s any life left inside.

  • Reply aimee parquette March 15, 2016 at 2:10 am

    Hello, I just bought a set of luffy balls and I am looking for a straightforward list of directions to get them started. From what I’ve read this is what I plan to do: 1)In a bowl of clean water (not tap water), gently squeeze the balls underwater to clean them. 2) Place the luffy balls in my aquarium with the light on. They should start bubbling within 30 minutes. 3)Change water weekly for best results.
    Please let me know if I need to do anything else to get my luffy balls started. THANKS!

    • Reply Mari March 15, 2016 at 7:22 am

      Nope, that sounds fine! Although you shouldn’t really expect actual bubbling, they may float for a bit and then sink to the bottom but they don’t actually produce bubbles besides the air pockets that are left over after cleaning. Good luck! πŸ™‚

      • Reply aimee parquette March 23, 2016 at 3:43 am


  • Reply Dorshell October 29, 2015 at 9:34 pm

    Marimo balls are new to me and I look forward to learning and caring for them in my 50 gallon aquarium. My question is which fish can live with them in my 50 gallon aquarium?
    Thank you

    • Reply Mari October 30, 2015 at 12:39 pm

      Most fish are fine, as long as they don’t require super high temperatures or are herbivores. Goldfish, plecos etc. are a no but most schooling fish, corydoras, cichlids (again, not the herbivores) and really any community fish is fine. It’s more important to make sure the fish species are compatible!

      • Reply Dorshell November 3, 2015 at 7:38 pm

        Thanks so much!

  • Reply Kelly October 29, 2015 at 6:10 pm

    Hi! I just picked up a Mario last week and have been keeping it in tap water. Unfortunately the water quality in my building is awful and has a yellow tint to it. Can I use spring water in place of tap water? I imagine distilled and filtered water would not be a good substitute, but can you suggest anything? Thank you for your help!

    • Reply Mari October 30, 2015 at 12:40 pm

      I actually don’t think the tap water is that bad, they can deal with dirty water as it won’t always be clean in natural lakes either. πŸ™‚

      • Reply Kelly November 3, 2015 at 3:01 pm

        Hi! I guess you’re right in that a bit of dirty water won’t hurt the marimo. I was just concerned about the way it looks more than anything. I’ll keep it in there for a while and see how it goes. Thanks for your help!

  • Reply josh September 27, 2015 at 11:50 pm

    Hello! So i just bought a mamio(it was a steal, about 4-5 in in water for $10, and its real!) and learn all the care for it but have a question, I’m keeping it in the water side of a land water bonsi pot so the water is wide but isn’t super deep, ill change the water ~once a week, is it ok that about 3-4 millimeters stick up out of the water? will the water saturate the entire ball? Or if i need to i can propagate it into 2 smaller balls so they are under the water completely.

    • Reply Mari September 28, 2015 at 11:37 am

      Hi! That sounds like an interesting setup. If only a small part sticks out of the water I think they will be fine if the emersed bit stays properly hydrated. There’s no harm in trying anyway – if you see brown bits appear, you can still propagate it.

  • Reply Nikki August 18, 2015 at 4:36 am

    I have about 15 moss balls that I took out of a previous aquarium that was overwhelmed with a orange and brown like algae growth. I have been cleaning them well, but now they have it as well. I dismantled the aquarium and only have the moss balls left in a free standing vase with gravel. It is a very fast growing algae and keeps covering the vase as well. I bleach the vase to get rid of it there but what can I do to the moss balls? Any help is appreciated. Thank you.

    • Reply Mari August 18, 2015 at 7:50 pm

      Sorry you’re having so many problems with your moss balls! Before I can help you out with anything, I need to know what kind of algae you’re dealing with. If you Google “diatoms freshwater aquarium”, does it look anything like that?

  • Reply Daniel90 July 26, 2015 at 2:14 pm

    Hi Mari,

    I have an unhealthy marimo ball which starts to turned yellow-brownish 2 months ago. I saw you mentioned on picking off the brown (dead) parts and adding a bit of salt to the water to stimulate the Marimo’s growth. How can I actually do it? Do I need to cut the brown (dead) parts with a cutter? Or can I try to put it in a fridge? And secondly, I usually leave it in the office. Maybe the marimo has insufficient sunlight? Do I need to put it near the window once a while? Looking forward to your response and thank you!

    • Reply Mari July 26, 2015 at 4:21 pm


      You can cut the dead parts with a cutter or just a pair of scissors. If the dead bits go all the way inside the marimo you can also just pull them out with your fingers. Adding some salt should be enough, and be sure to just leave your Marimo alone as much as possible except for the occasional cleaning. They don’t need direct sunlight, so if it’s in a relatively light place (like near a window but not actually right next to it) it should be fine.
      Good luck!

      • Reply Daniel90 July 26, 2015 at 5:03 pm

        Hi Mari,

        Noted with thanks. Will inform you if I’m having other problems. Have a great day! =))

        • Reply Lori July 26, 2015 at 6:43 pm

          I have also found that keeping the water fairly cool/cold helps the Marimo ball’s green color return. My sister’s Marimo was turning brown and she changed the water 2-3x a day. While that seems too often, her glass container was small and her house is not that cool. She said her Marimo changed back go bright green. Good luck!

          • Mari July 27, 2015 at 11:36 am

            Great tip! If the space the marimo is in it can definitely help to keep the water a bit cooler, although putting it in the fridge is usually not necessary. πŸ™‚

  • Reply Cat July 15, 2015 at 4:06 am

    Hi there! I am thinking of housing a marimo and a betta together and bettas need their water to be between 24Β°c and 27Β°c. I was wondering if I kept the water around that temperature, would the marimo be alright? Your page helped me quite a bit so thank you so much. (PS. I will be having a 5 watt aquarium heater, would that be alright too? Thanks again)

    • Reply Mari July 15, 2015 at 9:26 am

      Hello! If you keep the water at the lower end of the betta’s preferred temperature range it should be fine. I’m not sure if 5 watt is a typo, because that’s not nearly enough unless you’d want to heat up something really tiny. Bettas require a setup of at least 5 gallons which means a heater of at least around 25 Watt. Good luck!

  • Reply Cam July 9, 2015 at 2:20 am

    Hi Mari,

    I need a bit of advice. I have quite a few marimos ranging in different sizes in a 10 gallon tank that’s about 20 feet from my window. My window usually gets evening sun. I have a submersible LED strip with 24 LEDs in my marimo tank, that I got really recently. For maybe 2 months before I ordered the LED light I was using a lamp with a 60 watt house bulb which proved to be too much because they started to turn a slight golden brown. I removed the lamp, replaced the bulb with an aquarium appropriate bulb and am now using it for something else. For about 3-4 weeks, the marimos were in the tank without any light except for through the window and the slight brown tint turned a bit grey. I think 2 weeks ago I finally received the LED strip(due to shipping issues). After situating it in the tank, I was researching LEDs and found(this may not be true) that not all LEDs are appropriate for growing aquatic plants and that it’s undetermined how LEDs should be distributed in tanks opposed to the rule of watts per gallons.

    During the time I had been waiting though, I found a seller and couldn’t pass up the opportunity to snatch 2 very large marimos. Because marimos take so long to grow to the size that I bought, I want to take very good care of them. Should I wait to see if the LEDs are enough to help the others fully recover before I purchase another lamp and bulb, or go ahead and buy them to avoid the chance that they’ll go downhill/nothing will change?

    • Reply Mari July 9, 2015 at 8:24 pm

      Hello! Marimos don’t require that much light (I usually just recommend placing them near a window but not in the sun), so I personally think you would be fine waiting it out. I usually see broad spectrum LEDs recommended for aquariums/growing plants, not sure if that’s what you bought (I’m also not a lamp expert at all unfortunately) but because Marimos are fine with just natural light as well I don’t think there should be a big problem.
      Good luck!

  • Reply Nero June 21, 2015 at 10:17 am

    Hello! I just bought a Marimo from a convention. This person was selling them for 18$. It had a slash in it and it kinda fell apart when i fiddled with it slighty, im very anxious right now. It floated for a night yesterday and floated back down. this morning i accidentally ripped it, it has 3 cracks. For some reason now its not even floating when i squeeze the water out ;-; i dont know what to do.

    • Reply josh September 27, 2015 at 11:40 pm

      They aren’t supposed to float…
      Hope this helps!

      • Reply Mari September 28, 2015 at 11:34 am

        Oh dear, it seems I missed Nero’s original comment and never answered it – or did I answer it in another place? Hope I did!
        It’s not true that they’re not supposed to float, but they usually don’t. When you squeeze the water out they will usually float afterwards, but with cracks in them that’s not to be expected. I hope the marimo turned out okay!

  • Reply Anthony June 12, 2015 at 9:05 pm

    Not really understanding what I had bought, I rather stupidly flattened my Marimo thinking I could encourage it to grow on bogwood!

    Now I know better and want to ‘reball’ as it were. Is this possible? Can I just gently keep rolling them? Is there some technique?

    • Reply Mari June 17, 2015 at 7:02 pm

      Marimo can grow in a flat form, but if you want it to become round again you can just keep rerolling it, yes! There’s no specific technique, you just have to be careful and have some patience! Good luck. πŸ™‚

  • Reply slim617 May 22, 2015 at 3:08 am


    i need some advice on marimo..

    I have put my marimo ball through hell.

    I lost it at one point, but found it later, without any water for about a month or longer.

    I put it back in water, it was still lightly green with a small amount of white coating. It later developed some black spots.

    So i did the massage and cleaning for a couple of days, the color was still shade of white and green –

    BUUUTTT, i again.. did something.. i left it somewhere that received too much light.

    NOW its white and has greenish in the middle.

    should i pluck the white off till its green again?

    i followed your instructions, till the point.. i left it with too much sunlight.


    • Reply Mari May 22, 2015 at 5:41 pm

      Hi, sorry to hear you’re having problems with your marimo! I would trim/pluck away the white and then try to leave it alone as much as possible. Just put it in a nice well-lit but not sunny place and change the water regularly and it should hopefully recover! Good luck.

  • Reply Lori May 17, 2015 at 6:42 am

    I keep my five small (about 12 mm) Marimos in separate glass containers with aquarium gravel at the bottom. I noticed a few of the Marimos are turning slightly brown on the surface. I change the water frequently, at least once a week and I avoid direct sunlight.

    I read that carbonated water is helpful to Marimos because of the carbon dioxide. I also read that adding sea salt is also beneficial. So the last time I changed the water, I put in carbonated mineral water and a pinch of sea salt. Since Marimos grow very slowly, how soon would any change in color (from brown to green) be noticeable? Thanks in advance for your response and advice.

    • Reply Mari May 17, 2015 at 11:40 am

      Sorry to hear you’re having problems with your Marimos! I think you’re doing the best you can right now to get them back in a healthy state. I don’t think the brown hairs will change back to green again (as they’re dead), but I think you’ll see some change within 1-2 months, the new parts of the hairs should be nice and green.
      Good luck!

      • Reply Lori May 17, 2015 at 8:05 pm

        Thanks for your response Mari. I read that you can carefully remove some of the brown/dead exterior of the moss ball and then gently reshape it. I tried doing that on my son’s moss ball since it was mostly brown (one small green patch), but I was afraid of doing too much to it so I only removed a small amount. I’ll just continue to follow your directions and hope I see improvement in 1-2 months. Have you heard that carbonated water is helpful? Thanks again for your great website!

  • Reply Faisal May 7, 2015 at 3:26 pm

    Hi, i have 3 medium sized marimos. One has a split that almost cut it into half, and its texture is gooey and not very firm. I tried to roll it, but the split gets worse πŸ™
    Its colour is dark green with brown patches on it. I would love to show you the pictures, but i dont know how to post it. Is my marimo dying? πŸ™

    • Reply Mari May 10, 2015 at 10:54 am

      Hi, sorry to hear you’re having problems with your marimo! It doesn’t sound too healthy to me πŸ™ I don’t know if you can still save it, but I would split it into two marimos and do frequent water changes and possibly add some sea salt to try to revive it. Good luck! I hope it works out.

      • Reply Gunner April 10, 2020 at 1:52 pm

        I see a lot of folk advertising wood sculpture bonzi with moss balls as the foliage… what do you think of that? Will it work?

        • Reply Jennifer Doll April 10, 2020 at 5:19 pm

          Hi Gunner,

          I don’t have any experience with terrestrial bonsai at all, but I do know that marimo moss balls need to be constantly wet in order to stay alive. I guess if you were really on top of your mistings, then this could hypothetically work? But I honestly think it would be more worthwhile to go with tried-and-true terrestrial plants. If you meant replicating bonsai with driftwood for your aquarium, then I have seen much more success with Christmas moss (Vesicularia montagnei) and Micranthemum tweediei ‘Monte Carlo.’
          Good luck and happy fishkeeping!

  • Reply Maize May 5, 2015 at 10:48 am

    Hey there, I am Maize, i bought 2 little marimo balls through the internet (about 1.2 cm per each), and i found out that my marimo balls are quite different from yours, yours look like soft balls and they are very green, mine are just like some thin ropes tied up together and they are in dark green color, i don’t know how to upload the photo here so i can just describe these to you, lol.. i just want to know if my marimo balls are real or not. Thanks:)

    • Reply Mari May 5, 2015 at 11:21 am

      Hello! Since you can’t upload a photo through the comments, I’m going to ask you to search “Java moss ball” on Google images and see if that looks anything like your moss balls. If they do, then your moss balls are not made of Cladophora algae but of actual aquatic moss and thus not real Marimo. That seems the most likely explanation from your description. If you’re still unsure, you can mail a photo to aquariadise(a)gmail(dot)com πŸ™‚
      Hope that helps!

  • Reply Val April 25, 2015 at 10:53 pm

    Hi there, I really want to get some of those cute moss ball, Not a lot of people in my country knows them so it’s hard to find them, I recently stumble across one person who is selling “seeds” of marimo, here’s a photo of them they look very dehydrated, but he said that once placed in water they would start growing normally, I would like to know if those “seeds” are viable or if it’s a scam


    • Reply Mari April 26, 2015 at 12:49 pm

      I have honestly never in my life heard of Marimo seeds; is he talking about actual seeds like from a flower or are they just really really tiny Marimo balls from what you’ve gathered? If they’re micro Marimos then it doesn’t necessarily have to be a scam, but I agree they do look very dehydrated and more like fish pellets than Marimo balls to me haha! I’d personally pass on this one, because even if they’re not fake it will take VERY long for them to grow into regular sized Marimos (they only grow ~5mm a year). In my country there are quite a few webshops that are dedicated to selling aquarium plants; not sure if they have those where you are, but they usually stock Marimo balls for a reasonable price so that may be an option for you.

      Good luck! πŸ™‚

      • Reply Val April 26, 2015 at 5:04 pm

        Thanks for answering, yes, they are tiny marimos, that’s why he call them seeds, I believe they are like 5mm each. When I asked him about viability, he told me that it was at least an 80%, and when tossed into the water, they would start transforming after 5 days as they hydrate. I’m from Chile, and the cost of import plants is really high, that’s why it’s not an option for me now. This guy is selling 100+ micro marimos for 15usd, I don’t mind waiting for them to grow, cause other people sells 1-2cm marimos for 6usd/each. But what I’m worried about is if they are really start growing once hydrated.


        • Reply Mari April 27, 2015 at 1:16 pm

          I’ve never heard of that. It would be very interesting to see what happens if you do buy them, although I can give you no guarantee this is not actually a scam. I’m pretty sure Marimo balls don’t survive being dried out and I personally wouldn’t buy them, sorry! Good luck acquiring Marimo balls, though, hopefully you can find a few πŸ™‚

  • Reply Heero April 16, 2015 at 12:50 am

    Hi Mari,

    I’ve kept my marimo for about 6 years now and it’s been looking kind of brown lately so I tried to pick off the brown spots, but I’m having trouble taking it off. Any tips on how to take it off without hurting it?

    Also, I think it might be fake because the hair is somewhat coarse and stubby and it’s not as squishable as I imagine it to be. But can it be fake if it’s browning?

    • Reply Mari April 17, 2015 at 6:09 pm


      That’s odd! It can be fake if it’s browning I guess, because of brown algae growing on it. Fake Marimo is usually a plastic ball with stubby hairs glued to it, so if it feels anything like that I think you’re definitely dealing with a fake. If you can really pluck parts out then you’re probably fine. I take brown bits off with tweezers and then re-roll the Marimo if necessary.

      Hope that helps, and hopefully it’s not a fake!

      • Reply Heero April 26, 2015 at 11:58 am

        Good news, Mari! It’s not fake. I successfully took it apart. I removed the brown spots and found that the outer coat is way lighter than the inside. I’ve added a bit of salt into the water to help stimulate the growth; will moving it to a cooler, darker place hinder the growth?


        • Reply Mari April 26, 2015 at 12:44 pm

          Okay, that’s great! What you’ve done so far sounds good. I’d put the Marimo in a moderately lit place now; so not on a windowsill or anything like that, but just somewhere on a table or desk. Cooler water doesn’t bother them, as they naturally occur on the bottom of lakes where it’s obviously pretty chilly!
          Good luck, hopefully things work out for your Marimo haha πŸ™‚

  • Reply Nikki April 15, 2015 at 8:23 am

    I bought 2 little marimo balls in a small bottled up glass container. it is okay to leave them there? or is it best to transfer them in a bigger bottle with no lid? thanks

    • Reply Mari April 17, 2015 at 6:06 pm

      You can leave them in there if you can change the water regularly. A bigger container with a lid would probably be best though! Good luck πŸ™‚

  • Reply Ali April 2, 2015 at 4:19 am

    I’m currently doing my research on marimo moss…
    My plan is to place my marimo moss ball in a 1.5gallon bowl with a water lily. My first question: Will I still have to change the water weekly? My second question: When and if I need to use salt to help my marimo moss ball feel better, will Epsom salt be ok?

    • Reply Mari April 4, 2015 at 3:28 pm

      I’m not familiar with keeping water lilies, so I unfortunately can’t tell you much about that. You do still have to change the water weekly assuming it’s not filtered. If you use salt for your marimo, I’d just go for regular aquarium salt! Good luck πŸ™‚

  • Reply louie March 30, 2015 at 7:14 pm

    should I take my memo ball out of my tank and put it in a bowl and add salt how much do I add to the water

    • Reply Mari March 30, 2015 at 7:25 pm

      I’m not sure, why do you want to take it out of the tank?

  • Reply rachel March 26, 2015 at 1:36 pm

    I bought my first large marimo and when I got it in the mail it looked abit sick.. It smelled a bit and I’m pretty sure marimos don’t really smell. and It had some areas on the outside that were a kinda a dark off green gooey mold-like. I washed the marimo and it was filthy. But I’m not sure if it was rot or a hostile algae. I carefully tried removing as much of the dark area as I could and it actually got into the inside as well. I couldn’t remove it all because there’s quite abit spread but I think I did my best. There was also what looked like little white dots on the inside of the marimo when I pulled it open.. What else could I do? Is there still a chance my marimo will heal?
    And would salt water benefit? how much salt would I use to water?

    • Reply Mari March 26, 2015 at 9:58 pm

      Sorry to hear you’re having problems with your marimo! Salt water is usually used when a marimo is turning brown, what you’re dealing with here sounds more like it’s decaying a bit, although I can’t tell you for sure without actually seeing it. Salt won’t hurt, though, so you can start by adding a big teaspoon per liter (3,5 per gallon) and see if it helps. I think your marimo can heal just fine if you removed the bad bits and they don’t come back. Marimos don’t mind being pulled apart luckily! Good luck πŸ™‚

  • Reply Ashley March 25, 2015 at 5:55 am

    Your article is very useful and convinced me to get a Marimo! Now for questions: you talk about them falling apart negatively and positively, so when it does fall apart, how can you tell if it’s healthy or not? Also, what’s the best to house them in? I want to put mine in a bottle type of thing (maybe a mason jar??) like I’ve seen in pictures, but I don’t know if that’s the greatest for them.

    Thanks in advance!

    • Reply Mari March 25, 2015 at 6:29 pm

      You’ll notice if it’s falling apart the bad way! It’ll be pretty gross, possibly brownish and just generally unhealthy looking while really disintegrating. You won’t really be able to re-roll it effectively.
      When it’s ready to split (falling apart the good way) it’ll just become increasingly lopsided until you can separate it. You’ll be able to roll the two “new” marimos into smaller versions.
      A mason jar would actually be fine it it’s not too small, and I’d also leave the lid off. Just do water changes regularly and it should work just fine. You can also use an old fishbowl if you have one lying around (as they’re unsuitable for fish anyway) or any other type of container really! Good luck πŸ™‚

  • Reply Destiny March 14, 2015 at 1:39 am

    Hi there. Thank you for all the helpful information! I’m thinking of purchasing a marimo in the near future from a pet store but if it turns out to be fake, do you think the store will allow me to take it back and exchange it for a real one?

    Also, I know you mentioned that tap water is fine for marimos but our tap contains more chlorine than other places. Should I use filtered water instead?

    Thank you!

    • Reply Mari March 15, 2015 at 7:43 pm

      If the marimo is sold in the plant section I think you can be quite sure it is real, unless the pet store flat out lies to you. If you’re unsure, you can just ask them!
      Tap water should be fine for your marimo as well. You can just use a dechlorinator as you would in an aquarium if you’re unsure! Good luck πŸ™‚

      • Reply Roland Wee December 26, 2015 at 1:55 pm

        I use mineral for sometimes and i find it quiet good as my marimo is growing fine., and green.,very happy indeed.,

        • Reply Mari December 26, 2015 at 9:50 pm

          Very interesting, thanks for sharing!

  • Reply Jenny March 11, 2015 at 11:32 am

    Are marimos really soft? And is it normal if their color is not that dark green? Mine is light green.
    Also it has brown pigments at the tips of its hair. Is this okay?

    • Reply Mari March 11, 2015 at 10:06 pm

      Marimo are not super soft, they are squishy but firm. The color can vary, but if it’s too pale it can be an indication of disease. Your marimo doesn’t sound super healthy from your description, but if you just got it I think it should recover with good care (as described in the caresheet)!

  • Reply Isabella January 7, 2015 at 1:04 pm

    Hi! I recieved 2 marimo balls for christmas this year, and they are beutiful and green! But this morining i noticed white strings growing out of them and they are stretching towards the surface of my bowl. I have them in a LARGE bowl in my room with rocks on the bottom and i make sure to change the water and clean them out weekly. Am i doing anything wrong? What are those white strings growing out of my marimo?

    • Reply Mari January 7, 2015 at 3:46 pm

      The bowl/cleaning sounds fine so I don’t think there’s any problems there. Do the write strings look anything like the hostile algae pictured in the article? It sounds like that may be what they are, although I can’t tell you for sure. You could try removing them carefully without damaging the marimo. Good luck!

      • Reply Isabella January 7, 2015 at 10:04 pm

        Thank you so much for the help!

  • Reply Donna December 29, 2014 at 6:04 pm

    I have a small tank with about 8 medium marimos and 10 nanos. They started getting a little deep in color, so I’ve added more artificial light for about 12 hours a day. Now I am seeing clear bubbles on a few marimos and some bubbles floating on top of the water. After capturing a few bubbles, they seem to be slimy. They do not appear to be air bubbles.

    • Reply Mari December 30, 2014 at 6:20 pm

      The increase in artificial light could mean your Marimos have started producing oxygen bubbles, that would be the most logical explanation. However, if they really don’t appear to be air bubbles I’m afraid I’m not sure either!

      • Reply Donna December 31, 2014 at 3:02 pm

        Are oxygen bubbles the same a “pearling”?

  • Reply Lisa December 16, 2014 at 10:48 pm

    Hi, I got my Marimo just over a yer and a half ago. When I first got them they were a wee bit discoloured but now are a lovely green! After a few months with them I noticed 3 tiny snails in the case with them. Sadly 2 got lost in cleaning, but 1 (Dave) is now considerably bigger in just a year. Was looking tonight and there are 2 more tiny snails who have somehow magically joined Dave! I was just wondering if u know where the snails came from in the first place and how they are appearing as if from no where?

    Thanks so much for this blog, it’s extremely helpful!

    • Reply Mari December 19, 2014 at 11:53 am

      Thank you!
      Dave (great name, too) is most likely a pond snail, they come with plants occasionally. The eggs or baby snails are on the plants and can hitchhike into your aquarium this way! If you got any more plants those may be the cause of the other snails appearing, but I’m pretty sure snails can also reproduce asexually, which means Dave would be the mom/dad, haha. Try looking for little translucent patches of “jelly” with little specks in them, those are snail eggs.

      Good luck with Dave and his (possible) offspring!

  • Reply Courtney McIntire December 3, 2014 at 9:26 pm

    Would you use regular table salt or aquarium salt for the brackish water?

    • Reply Mari December 3, 2014 at 10:21 pm

      I actually use dishwasher salt as it’s free of any additives and cheaper than aquarium salt. I’m not sure if it would be a problem to use regular table salt for Marimo balls, but if you want to be 100% safe aquarium salt, dishwasher salt or another kind of salt without additives is probably your best bet!

  • Reply Brithyst December 3, 2014 at 6:07 am

    Hey, I’ve had an Marimo ball for almost 2 years. Now it’s yellowing and soft and falling apart, lots of the algae gets sucked into the filter(it’s falling apart) at first it was relatively healthy then after awhile I noticed one of the stones were crushing it and it was falling apart, super fragile. After losing most of its parts which just break down into smaller and smaller balls and inventually the smaller balls fall apart until all you can see is algae specks swimming around in the water. I give it enough light,doesn’t bother it much (fragile) should I squeeze it back into an extremely small ball?

    • Reply Mari December 3, 2014 at 10:19 pm

      Sorry to hear you’re having trouble with your Marimo! I think you could try squeezing it back into a small ball, but I’m afraid there may not be much you can do πŸ™ good luck, though, it may still recover with some love!

  • Reply kristen November 7, 2014 at 4:04 pm

    Hi Mari, I was rolling my Marimo ball and I accidently split it but not all the way. should I split it all the way or just keep trying to roll it together? Or will it even grow back together? It is still nice and green. thanks kristen

    • Reply Mari November 18, 2014 at 8:33 pm

      So sorry for the late reply! I’m guessing by now you’ve already made a decision, but in my experience splitting it works best. Trying to roll it back together is also a possibility, though, it’s just much easier to roll two new marimos. If they’re still nice and green they should be absolutely fine!

      • Reply Nero June 21, 2015 at 10:32 am

        mine isnt getting any rounder when i try to roll it. every time it gets back into the water it kinda falls apart and dosent float. sorry if i commented twice but im very nervous about my marimo situation. it had something like gooey stuff inside of it when i accidently ripped it open. but its still green. just this tiny spot it has white little strings on it?

        • Reply Mari June 21, 2015 at 3:46 pm

          I really can’t tell you more than clean water, plenty of light (but not direct sunlight) and possibly some salt. Leave the marimo alone as much as possible and don’t try to roll it too often as fiddling with it too much can make things worse. If nothing works you can try splitting it into multiple smaller balls or it may just be dying. Sorry I can’t be of more help! Good luck πŸ™‚

  • Reply SS October 28, 2014 at 12:45 am

    Great information!

  • Reply Eri September 3, 2014 at 3:57 am

    Hello! I have some pesky cats that like to get into my marimo bowl and sometimes spill it over. I moved my marimo into the sun for a few days (by accident) and I have accidentally overexposed my poor marimo! How would I treat this overexposure?

    • Reply Mari September 6, 2014 at 12:33 pm

      Hi! A bit of overexposure to the sun usually doesn’t kill a marimo. I would move it to a light but not sunny place and keep the water extra clean. It’s possible for some parts to turn white and die off after overexposure to the sun, but your marimo should recover just fine!

  • Reply kaylee August 9, 2014 at 5:12 am

    I have just ordered some marimo. When I first look at them they were so cute and small. But I was wondering if you any websites online had Marino necklaces. Ones that I find are way expensive.

    • Reply Mari August 10, 2014 at 3:43 pm

      Hi! I know marimo necklaces are sold on Etsy, but I wouldn’t personally recommend buying them because a necklace isn’t really a good environment for a marimo ball to live in. You could wear them around your neck for a while, but you’d have to take the marimo out eventually because they can’t grow in there. Marimos do way better in vases and aquariums!

  • Reply Personette July 19, 2014 at 2:42 am

    Hi! I recently just got a Marimo and split it into three. However, I am worried that one of the pieces is too small and won’t survive. About how small can Marimos be split safely? Additionally, am I supposed to wait a few days before rolling the new Marimos into a ball? Finally, how do I tell if my Marimos are “happy”? Sorry for asking so many questions… Thank you for your wonderful blog!!

    • Reply Mari July 19, 2014 at 1:05 pm

      Hi! I’ve seen really tiny marimos, so I think the smallest one will be fine. You should gently roll it into a ball immediately after splitting and it should be okay. Your marimos are “happy” when they’re bright green and don’t have discolored patches. If you don’t see anything unusual, they’re probably doing well.
      Good luck!

  • Reply Michelle June 24, 2014 at 10:11 am

    I have bought two marimo. I can feel one of my marimo is soft while the other is abit harder. Is this normal?

    • Reply Mari July 13, 2014 at 3:56 pm

      If both the marimo balls look healthy and green I don’t think there is a problem! They are not all the same.
      My apologies for the late reply!

  • Reply ChibiSama08 June 5, 2014 at 3:28 am

    Hello! I just bought my first Marimo online and had a few questions about it to be sure of some things.
    I was wondering if water with a higher level of sulfur would be ok to keep Marimo in. I live in Florida and our well water has a higher level of sulfur than other places can have, I just wanted to be sure it was ok to put him in it or if I would have to buy spring water.

    • Reply Mari June 5, 2014 at 2:19 pm

      Hi! I don’t have personal experience with water with higher sulfur levels, but marimo is a type of algae which means it’s pretty hardy. I’d go ahead and try it, I don’t expect any problems! If you do start seeing discoloration, you can always switch to spring water. Hope that helps!

      • Reply ChibiSama08 June 6, 2014 at 1:00 am

        Thanks so much! πŸ˜€

  • Reply Brooke May 30, 2014 at 4:31 am

    Ok so I have 3 questions is it okay to have a Marimo in an aquarium with a baby turtle? And I heard that the Marimo will also keep the tank pretty clean for you is that all true? And can a Marimo be in a fish tank with a Beta fish?

    • Reply Mari May 30, 2014 at 11:48 am

      Hi! Marimos are fine to keep with turtles and bettas. Unfortunately, though, they can’t help you keep the tank clean. Live plants like marimos are good to have in your aquarium because they help keep water values stable, but the cleaning is up to you. Even with a marimo you have to do regular water changes!

  • Reply Janis March 24, 2014 at 7:13 am

    Hello! A few quick questions.
    1) I picked up a marimo at my local petsmart (pet store) today for $8 – it’s pretty large, maybe 2 inches diameter, somewhat lopsided, has little air bubbles stuck to the surface hairs, and is a bit brownish on the bottom. I’m wondering if its real since I read that it takes years for a marimo to grow this big. The hairs aren’t scratchy or coarse, but they aren’t silky soft either. I’m not sure how soft/squishy a real marimo should be! Any objects or textures you could suggest as a point of reference?

    2) Is bottled/filtered water safe for marimos? My house has a filtering system installed that removes a lot of the minerals normally found in tap water.


    • Reply Mari March 24, 2014 at 6:20 pm

      Hi! I can definitely understand your confusion. A fake marimo is often made of a plastic ball with synthetic hairs stuck to it. You can usually kind of feel the plastic ball inside. A real one doesn’t have silky soft hairs but it should be pretty squishy! I can’t really compare it to anything but if it’s lopsided you should kind of be able to roll it into a round ball between your hands. The shape can be changed!

      I’m pretty sure bottled/filtered water is fine, although I don’t have personal experience with it! The food the marimo uses, like nitrate, should still be present in the water in very small amounts.

      Hope that answers your questions! Good luck πŸ™‚

  • Reply Tricia March 13, 2014 at 7:46 am

    How do I know my Marimo is real or fake

    • Reply Mari March 13, 2014 at 3:07 pm

      The fake marimos I’ve encountered all didn’t feel like real ones at all! Real marimos are very soft and squishy, whereas fake ones usually have harder hairs which are sometimes quite obviously plastic. You can also pick a real marimo apart, but that may not be the best test! Hope that helps.

  • Reply Snow Lee March 1, 2014 at 3:34 pm

    I wanted to ask~ i do not own a marimo yet but i am interested. But before i get a marimo, i wanted to ask if it is safe to buy a mini marimo in those small battle(phone straps). Since the bottle is always closed therefore i dont think there will be much oxygen going into the bottle. Will the mini marimo be able to survive? or is it a bad idea to keep a marimo in those small-closed up bottle? And when i got a marimo, do i need to put anything into the water? I saw some images on google that there were some liquid thingy that was for marimos.

    • Reply Mari March 1, 2014 at 5:01 pm

      I think a marimo could probably do well in one of those phone straps for a while, but after a while you’ll probably have to take it out. Like you said there probably won’t be too much oxygen in there and there’s no way to properly clean the water. I’d personally go for a normal marimo instead, maybe in a pretty vase! You could try the phone straps, but I can’t guarantee succes.
      Hope that helps!

      • Reply Snow Lee March 4, 2014 at 12:49 pm

        Thanks for your reply!

      • Reply Sally February 27, 2020 at 9:39 am

        Hi! Um, I’m planning to buy some marimos soon, and I’ve got some questions:
        1. Is it a good idea to keep my marimo in rainwater? I live in a hot, tropical country and it’s been raining a lot recently, the tap water here is heavily chlorinated, so I have to use either rainwater or bottled water…
        2. Since I probably have to keep my marimo cool, can you recommend types of freshwater fish that can withstand cold temperatures?
        3. If I decide to not have fish with my marimo, should I add liquid fertilizer to my marimo’s tank or should I just add water from my fish tank?

        • Reply Jennifer Doll February 28, 2020 at 6:28 pm

          Hi Sally,
          1. I think rainwater will cause you more problems than what it’s worth. There is a lot of room for possible contamination, and you’ll never truly know what’s in the water unless you look under a microscope. My first option would be the bottled water. Even using a water conditioner to remove the chlorine from your tap water will introduce unwanted nutrients into your tank that could cause algae blooms and other water quality issues.
          2. White Cloud Mountain Minnows! They are a perfect hardy species that go well in smaller coldwater tanks. We have a full article about them here.
          3. If you really want to have a beautifully planted tank, fertilizer will help with growth.
          Happy fishkeeping!

  • Reply Brittany January 31, 2014 at 3:01 pm

    Hello! I actually somehow had this type of moss grow in my aquarium on my terra cotta pots. I was wondering how it got there without having a marimo ball. Not only that, but I was wondering if there’s any way to transplant it onto something (like the terra cotta pots from the ball). One more thing, how long does it take this algae to grow and how often do you have to move and reroll it?

    • Reply Mari February 3, 2014 at 9:52 am

      Hi! I know that you can cut open marimo balls and have them grow on another surface. This also happens in the “wild” sometimes, whether they grow round depends on the situation. So yes, you can definitely transplant them onto something else! Some people use them as little algae carpets or to cover rocks, driftwood and decorations.
      If you want to keep the marimo in its ball shape you can just roll it around a bit whenever you clean the tank so it stays round and doesn’t get brown parts. Marimo grows very slowly, only around 5mm (0,2 inch) a year according to most sources!

  • Reply shelly partain January 25, 2014 at 2:25 am

    do they do well with turtles. I was thinking of butting one in with my yellow belly slider

    • Reply Mari January 27, 2014 at 5:16 pm

      I have no experience whatsoever with turtles, but I think it’s worth a shot. Marimos usually do well with animals that are not too destructive, so as long as your turtle doesn’t have a taste for algae there’s a good chance it’ll be fine. If it does turn out it doesn’t work, let me know and I’ll add it to the article!

  • Reply Jacqui January 17, 2014 at 6:35 am

    Bettas are tropical fish and all, so I was wondering if you could put marimos in a heated betta tank? What would happen to a marimo that is in a consistently warm environment, say around 78 degrees? I’ve seen people keep marimos in betta tanks, but then again, I’ve also seen people keep bettas in vases, so I just wonder how optimal it is for both the plant and the fish.

    • Reply Mari January 17, 2014 at 3:50 pm

      Marimos do not naturally occur in places with such high temperatures, and I don’t think it’s optimal for them. I did keep a marimo in a heated betta tank for an extended period of time, and it didn’t seem to be affected too much, but they will probably grow better when you just keep them in a cooler tank or a separate vase.

  • Reply sook han January 14, 2014 at 4:23 am

    my marimo getting apart. they not in a ball shape anymore.. >< like a loosen ball!! how???!!

    • Reply Mari January 14, 2014 at 10:22 am

      You can fix your marimo falling apart by regularly picking it up and gently rolling it between the palm of your hands. That way it should get its ball shape back eventually!

      • Reply yik sook han February 10, 2014 at 12:18 am

        my marimo ball eventually become flat in shape.. i did what u said but i sont even recovering.. omg! what shouldi do? it isnt in any yellowish or grey.. it just getting farr apart .. TT

        • Reply Mari February 10, 2014 at 7:27 pm

          Oh dear, so sorry to hear that! The marimo is still healthy, it’s just grown into another shape. If you roll it between your hands to make a ball regularly, it should eventually go back to its original shape. Have you been doing that? If you need to, you can also make it into two separate marimos.

  • Reply Daniel Torres Lopez January 7, 2014 at 1:41 am

    Hi, have 5 marimos and 1 month ago they stop to bubbling at all, they are green and normal the only difference is they are not bubbling like before, what happen with my marimos? thanks

    • Reply Mari January 7, 2014 at 10:34 am

      The bubbles are caused by air that was trapped inside the marimo releasing. If they’re not bubbling any more, that probably means all the air has been released due to them not having been out of the water. If you take them out, wash them and gently squish them a few times, there’s a good chance you’ll start seeing bubbles again!

  • Reply Anna December 8, 2013 at 3:37 am

    I currently have installed a bubbler in the marimo’s container. Is it good to have the water aerated or for it to be still? The one ball seemed to be turning a bit brown and falling apart and I didn’t know if that would help it?


    • Reply Mari December 9, 2013 at 1:23 pm

      While I think it would be good for the Marimo if the water isn’t 100% still all the time, bubblers are not usually recommended for planted tanks, as plants need CO2 to grow and bubblers lessen the amount of CO2 in the water. Now I don’t think Marimos need that much oxygen to thrive, so I guess you could see how it goes! If the Marimo turns nice and green, I’d leave the bubbler in. If it keeps turning brown, I’d take it out and maybe try a salt treatment!

  • Reply Pip December 2, 2013 at 11:58 pm

    I have just bought 3 Marimo Moss Balls from Ebay for my tropical fish tank. I have mainly small fish, but I do have 2 Siamese Algae Eaters, and a Bristlenose Albino Plec, and so far so good. I just put plenty of Cucumber in my tank and they prefer to eat that instead.
    I just wondered though. I have seen pictures of these little glass terrariums with marimo in them and some of them also have shrimp with them. How do you take care of the shrimp and keep the temperature of the water right. Filtering too. Can shrimp deal with no filter and the water cooling to room temp, and the moss balls too.
    Thanks Mari.

    • Reply Mari December 3, 2013 at 4:37 pm

      Great to hear your marimo balls are doing fine even with the Siamese algae eaters and pleco. It’s definitely true that not all of them develop a taste for marimo, especially when they’re supplied with plenty of cucumber!
      I’ve seen the glass terrariums with shrimp you’re talking about I think. I wouldn’t recommend getting them. Although dwarf shrimp, especially cherry shrimp, are quite hardy and do fine at room temp (as do moss balls), the temperature will likely fluctuate too much and with just a marimo there aren’t enough plants to keep the water clean. It’s possible to keep shrimp in unfiltered tanks, like this one (which is perfect for shrimp, and shrimp only!), but only when it’s heavily planted. In those little terrariums, it’s likely the water will just get too dirty for the shrimp.
      Small containers are perfect for marimos, because you can just replace all the water every week or so and they aren’t too sensitive to temperature fluctuations, but for shrimp it doesn’t seem like such a good idea go me.

  • Reply cassy October 30, 2013 at 3:10 am

    hi, i recently bought 2 mariso moss balls. have them in fish bowls with a betta. so far they havent done anything. they havent followed light and they arent bounching.. are we doing something wrong or just expecting to much??? their both a nice green color and in a good ball shape.. any advice would be appreciated.. thank u..

    • Reply Mari October 30, 2013 at 11:38 am

      Hi! Marimos don’t actually bounce – they do float when they’ve just been cleaned. If they’re nice and green and ball-shaped, you’re doing everything right with them so far πŸ™‚
      However, I really do not recommend keeping a betta in a bowl, as they usually can’t be heated or filtered properly. Bettas need at least a 5 gallon cycled aquarium with a heater, filter and weekly water changes! Pet stores will often try to tell you otherwise, but they unfortunately cannot be trusted to give you good advice. This article contains more info about what a proper betta tank should look like.
      Good luck with your betta and marimos!

  • Reply Julie August 30, 2013 at 2:41 am

    Hi Mari, thanks for the informative post! Can you tell me what kind of fish do well with marimo? I know bettas, but are there any others? I’m looking to set up a 7-10 gallon tank and would like some fish to go along (and get along) with my marimo!
    Thanks for your time,

    • Reply Mari August 30, 2013 at 7:36 am

      Small schooling fish like Microrasbora would be great for a tank that size and they leave Marimos alone. Shrimp, nerite snails, pygmy cory catfish, dwarf crayfish and otocinclus catfish are also all possible for a 7-10 gal with a Marimo. Because the tank is quite small, I’d choose 2 species and leave it at that. Good luck! πŸ˜€

  • Reply Ama August 28, 2013 at 9:50 am

    Hi, thanks for a great article. :3 Especially that there’s not much in the internet about marimo. But I have a problem. While squeazing the water out, two of my marimos released a sort of white foam. After that they got noticeably lighter and now float on the surface. Is it bad?

    • Reply Mari August 28, 2013 at 5:22 pm

      Thank you, glad you liked the article! πŸ™‚
      I think I’ve seen what you’re talking about with my own marimos, and although I’m not 100% sure I think the foam are just air bubbles that were trapped in the marimo and came out when you squeezed it. Then when you unsqueeze them, they suck in new air (like a sponge) and stay floaty for a while. If you gently squeeze them again while keeping them under water, do they start sinking?

  • Reply Jenebrith July 26, 2013 at 11:07 pm

    Hi Mari,
    Thanks for the article! It was a great help. Although, I’ve noticed that my marimo has these little “beads” growing on it. I’m not really sure what they are and didn’t know if they were another form of algae that grew on marimos. They are really easy to take off, but I’m still worried. Do you know what these could be? Thanks for any help!

    • Reply Mari July 27, 2013 at 10:05 am

      That sounds very strange! If you gently wash the Marimo and remove all the beads while doing so, do they grow back? I’m not sure what to think of this either, especially without a photo of the phenomenon. If you have a photo, you could mail it to aquariadise(a) and maybe that’ll make it easier to figure out what it is!

      • Reply Rachel February 24, 2015 at 6:55 am

        Hi, I just got 2 marimo from Petsmart a couple days ago and one of them has yellow/orange “beads” on it, as well as some strange white strings coming off of it and floating around (which, from earlier posts, I think might be hostile algae?). A lot of the other marimos at the store also had these “beads”, but the guy who worked there told me they were all healthy. Now I’m not so sure. Someone told me they could be snail eggs? Do you guys have any idea?

        • Reply Mari February 24, 2015 at 11:37 am

          Hello! Wow, that sounds pretty odd, I’ve actually never heard of “beads” on a Marimo (else it would be included in the article!). The white strings definitely sound like either hostile algae or dead Marimo bits. Without a photo, it’s pretty hard to tell you what the beads are. Most snail eggs look like a translucent blob with tiny specks inside, so I don’t think that’s what’s going on. You can try e-mailing me a photo at aquariadise(a), maybe then I can help you out!

  • Reply David July 7, 2013 at 12:25 am

    Beware of pletcos. I put one in my aquarium and the next day it was gone.

    • Reply Mari July 8, 2013 at 9:59 am

      Oh no! πŸ™ I’ll make sure to mention plecos a bit more explicitly in the article so people will avoid combining them.

  • Reply Michael July 4, 2013 at 3:22 pm

    Marimosan was bright green when first arriving; now is dark green. Had grayish blobs on surface which were picked off. Blobs haven’t returned but still dark green. Temperature o.k. and light subdued. Seem to like squishing and fresh water as needed. Salt was suggested to restore bright color but don’t know how much salt to add. Thanks for info.
    p.s. Goldfish are notoriously dirty, producing lots of goldfish poop.

    • Reply Mari July 5, 2013 at 7:55 pm

      I’m not sure if you have your Marimo in a separate container or in an aquarium – if it’s in an aquarium, you can temporarily separate it for a salt treatment. I’m not entirely sure how much to add either, but you could start out with a teaspoon per gallon. If that doesn’t work, you could work your way up to a tablespoon per gallon to see if that has effect.
      Good luck! πŸ™‚

  • Reply Cindy C. May 22, 2013 at 12:21 am

    Hi Mari,

    Thanks for the terrific article about how to care for a Marimo!

    I don’t own a Marimo, but I’ve recently become interested in buying several to – they’re fascinating little things, aren’t they?

    I’ve been reading that not all Marimo sellers are reputable – there are people on the Internet who roll little balls of Java Grass around ping-pong balls & try to pass them off as “authentic” Marimo balls.

    My question is; Can you provide some names of people who I can trust to sell me an authentic Marimo ball?

    Thanks so much!

    • Reply Mari May 22, 2013 at 7:55 am

      Glad you liked the article!
      I’ve never heard of people making “fake” Marimo balls before, but I can imagine it does happen πŸ™
      I live in Holland so I can’t really provide you with any names of people who are likely to be in your area. Thankfully it’s easy to recognize a real Marimo – they will be nice and fuzzy, whereas most other plants are more thread-like -, so you could try your local aquarium/pet store if they carry aquarium plants, and most eBay sellers will also sell you the real thing because they don’t want bad feedback. The cheapest option is probably Craigslist, though – I got my Marimos there for little over a dollar each, whereas on eBay and in pet stores you easily pay $8 for a tiny one! If you can find them on Craigslist (search for “marimo”, “moss ball”, “algae ball”, etc.), just ask for a photo of the product before buying. You could even reverse image search to confirm they didn’t just take a random photo from the internet. :p

      Hope that helps a bit. Good luck!

    • Reply sue June 24, 2013 at 11:06 pm

      Cindy, I got mine on Fast shipping, very healthy…I love mine!
      Oh, and thank you Mari for all this info! Bookmarked it!

      • Reply Mari June 25, 2013 at 4:35 pm

        Great to hear the article was helpful to you! πŸ™‚

        • Reply Nycole September 5, 2019 at 9:28 pm

          Hello~ wonderful article! I just bought my nano marimo but I notice it’s not producing bubble (pearling) around it. Is it normal?

          • Mari September 6, 2019 at 12:40 pm

            Yes that’s normal! Marimos generally only have bubbles right after washing them. πŸ™‚ Good luck!

  • Reply Izzy the Fish Girl May 15, 2013 at 8:45 pm

    I’ve kept marimo for years and LOVE the little things! I can vouch that they don’t work with goldfish as I tried some with my first goldfish only to find them torn apart. Now I have my marimo in a little glass bowl by my bed. I’ve even converted others to the way of the marimo! My boyfriend has one on his desk in his dorm!

    • Reply Mari May 15, 2013 at 8:49 pm

      I wonder how many innocent Marimos have fallen prey to hungry goldfish, haha πŸ™
      So funny your boyfriend has one too, hopefully this article will convert even more people to the Way Of The Marimo!

    Leave a Reply

    This site uses Akismet to reduce spam. Learn how your comment data is processed.