Stocking a 5-Gallon Fish Tank: An In-depth Aquarist’s Guide

Alison Page

Alison Page


Stocking a 5-Gallon Fish Tank

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If you’re thinking about setting up a 5-gallon (18.9 L) aquarium, it’s easy to get confused by the conflicting information spread around the internet and by aquarium stores. So, you’re not working with a lot of space, but you still have many options to choose from, believe it or not!

What are the best fish and invertebrates for a 5-gallon fish tank? How many fish can you keep? And can you have some plants, too?

Keep reading to find out everything you need to know about the best ways to stock a 5-gallon fish tank!

Key Takeaways

  • A 5-gallon tank is suitable for various fish and invertebrates but requires careful stocking to ensure a healthy environment due to size limitations.
  • Certain popular fish species like goldfish, tetras, and corydoras are not recommended for 5-gallon tanks as they need more space or are sensitive to water quality fluctuations.
  • Ideal inhabitants for a 5-gallon aquarium include betta fish, least killifish, cherry shrimp, dwarf crayfish, and small snails, alongside a selection of live plants that can create a thriving ecosystem.

Summary Table

Suitable Fish for a 5-Gallon TankDetails
Betta Fish (Betta splendens)A single betta fish is ideal for a 5-gallon tank due to their relatively lower activity levels and size. They thrive in planted tanks with hiding spaces but are solitary and can be aggressive, so they should not be housed with other bettas.
Least Killifish (Heterandria formosa)These small fish can be kept in a pair, but care should be taken as they may breed. They enjoy densely planted tanks and can live peacefully in small groups.
Cherry Shrimp (Neocaridina davidi)These colorful invertebrates are a great option for those not interested in fish. They are easy to care for and can reproduce in the tank, adding to the population naturally.
Dwarf Crayfish (Various Cambarellus spp.)Dwarf crayfish add personality to a tank and can be kept in a 5-gallon setup with adequate hiding spots. It's important to pick smaller species and limit the number to prevent overcrowding.
Thai Micro Crab (Limnopilos naiyanetr)Extremely small and less common than other species, these crabs do well in peaceful communities with plenty of hiding places and are suitable for experienced keepers.

Is 5 Gallons a Good Aquarium Size?

5-gallon aquariums are among the most popular tank sizes. This isn’t too surprising as they are small and can easily fit into pretty much any limited space.

A 5-gallon tank is the minimum tank size that can comfortably hold fish; some hobbyists have had success with 2.5-gallon (9.5 L) setups. However, that should only be attempted by experienced fishkeepers or used to keep shrimp or snails, which produce a lower bioload than fish. Any smaller than five gallons of water, you’ll encounter difficulties keeping a stable nitrogen cycle and providing your stock with enough room to swim. Even the smallest fish need space to move and explore!

Even though these tanks are small, they can still hold a lot of life. However, picking the perfect, healthy ecosystem choice for your 5-gallon aquarium can be challenging.

There aren’t many tropical fish species that will thrive in a 5-gallon aquarium, but you can still set up a lively and entertaining tank.

Here are the dos and don’ts of stocking a 5-gallon freshwater aquarium!

Fish Not Suitable for a 5-Gallon Tank

To prevent confusion, I’ve listed below some fish species that are often recommended as being suitable for 5-gallon setups but that actually need a much larger tank.

These species are either too active, grow too large, or cannot handle the unstable water quality that comes with a smaller volume of water.

Goldfish (Carassius auratus)

Goldfish Carassius auratus

Fancy goldfish need 20 gallons (75.7 L) of water per fish for the smaller varieties, with larger fish needing even more space.

Additionally, since goldfish are highly social fish, keeping only one per tank is not right. Most goldfish keepers recommend an additional 10 gallons (37.9 L) for every additional fish added.

However, given their heavy bioload, it’s a much better idea to aim for 20 gallons minimum per fish instead. So, goldfish of any variety are a definite no-no for a 5-gallon tank.

Slim-bodied goldfish grow far too large for a fish tank, especially a 5-gallon one. Since these fish can grow to over two feet long, they do best when kept in ponds or extremely large aquarium systems with other goldfish.

Danios and Minnows

Giant Danios

Danios and minnows will mainly stay towards the top of the tank, but they still need plenty of swimming and shoaling space. These hardy fish are some of the most active in the fishkeeping hobby and will quickly stress out in smaller tanks.

These species should never be kept in anything less than a 20-gallon (75.7 L) long tank where horizontal aquarium floor space is greater than vertical.

Dwarf Pufferfish (Carinotetraodon travancoricus)

Dwarf Pufferfish

Dwarf puffers are size-appropriate for a 5-gallon tank, but unfortunately, hobbyists can’t meet their need for good water quality and enhancement in such a small tank.

Smaller tanks can easily cause water parameters to fluctuate, given how little water there is. Advanced hobbyists may achieve better water stability, but dwarf puffers will also need an engaging ecosystem with decorations to keep them from getting bored.

For one dwarf pufferfish, a 10-gallon tank (37.9 L) is recommended. If you want to have more than one puffer, at least 20 gallons (75.7 L) is needed.


Cardinal Tetras

All tetras, including neon tetras (Paracheirodon innesi), cardinal tetras (Paracheirodon axelrodi), and black neon tetras ( Hyphessobrycon herbertaxelrodi), cannot be kept in a small tank. Even though these fish are some of the smallest available, they are still active schooling fish that need room to swim.

Like the white cloud mountain minnow, tetras become stressed when kept in groups of less than eight individuals. If you want to see these fish at their best, set them up in a larger, more extended tank with plenty of companions.


Fancy Guppies

Guppies, including Endlers guppies (Poecilia wingei), are usually kept in awful conditions in pet stores. That does not mean they can be shoved into a tiny nano tank!

These fish grow quite large. Not only do they get bigger than you think they will, but they’re prolific breeders. It doesn’t help that even if you buy all females, they might be pregnant right from the fish store or breeder and spawn in your aquarium.

The small space and limited scope for decoration of a 5-gallon tank also don’t allow the females to escape males constantly harassing them to breed.


Rasbora Het Harlequin rasbora heteromorpha freshwater aquarium fish

Rasboras also need larger tanks and greater numbers to thrive.

Again, it should come as no surprise that even the tiniest of rasboras, such as chili rasboras ( Boraras brigittae), still do best in large groups and spaces; the ideal tank size for a school of six chili rasboras is at least 10 gallons (37.9 L).

Larger species, like harlequin rasboras (Rasbora heteromorpha), need at least 20 gallons (75.7 L) to feel at home.

Corydoras spp.


Everyone wants to have corydoras in their aquariums! These small, active fish bring life and excitement to the bottom of the tank in a way that other species can’t.

However, all corydoras catfish species, including one of the smallest species, pygmy corydoras (Corydoras pygmaeus), are too active and/or too large for a 5-gallon aquarium.

Pygmy corydoras are also sensitive to poor water quality, which can be challenging to control in smaller setups. Since 5-gallon aquariums tend to have less water chemistry stability, any slight change can spell disaster for the pygmies.

Although many people recommend getting just one corydora as a “cleaner” fish for smaller tanks, don’t be fooled! Corydoras are schooling fish and need the company of at least four or five others of their species.

Some beginners to the hobby mistakenly believe that corydoras catfish are algae eaters that make a good cleaning crew for a tank. However, I’ve had many corys over the years, and I can confirm that they are not! You need to feed them a basic diet of tropical fish flakes and frozen meaty foods to supplement the nutrition they can take from plant matter and algae growing in the tank.

Corys are also surprisingly active for bottom-dwellers, spending much of their time foraging among plant bases and darting up to the surface periodically to snatch a gulp of air. So, the best-shaped tank for these cute little fish is a long, shallow one, and a 5-gallon aquarium is simply too small.

Large Snails

Mystery Snail Stress Slime

People always underestimate how much waste snails produce. In particular, the apple snail (Ampullariidae family) and mystery snail (Pomacea bridgesii) grow too large and produce a lot of waste. However, if the tank is adequately filtered with live plants and no fish, large snail nano tank setups can be successful.

To make life a bit easier on yourself overall, aim for bigger setups for larger snails. In a small tank, stick to nerite snails that can’t breed in freshwater.

The Best Ways to Stock a 5-Gallon Aquarium

A few fun nanofish and invertebrates will do wonderfully in a tank of this size.

However, remember that you must always cycle your tank before adding fish! In a 5-gallon aquarium, it’s easy to lose control of the water chemistry, which can prove fatal to the inhabitants before you even know there’s anything wrong.

Many of the species listed below can be combined as their bioload is relatively minimal as long as they are compatible. You can easily add a few shrimp or snails to pretty much any setup, though this might be different when fish are involved.

Here are some of the best fish and invertebrates for stocking 5-gallon tanks.

Betta Fish (Betta splendens)

betta fish

Betta fish are excellent fish for stocking a 5-gallon aquarium: they’re beautiful to look at, don’t require much extra maintenance, and fit perfectly in a standard 5-gallon setup.

These beautiful fish do especially well in planted betta tanks stained with plant tannins and filled with natural hiding places. Of course, keep in mind that they are aggressive fish, and you cannot keep two males together in the same tank.

If you want to branch out and try something different, you can also try other wild species of betta, such as Betta smaragdina, Betta mahachaiensis, Betta imbellis, or Betta siamorientalis.

Least Killifish (Heterandria formosa)

Least killifish

While you can keep a pair of least killifish in a 5-gallon nano tank, keep in mind that they might breed if conditions are suitable, leading to overstocking. In that case, you’ll need to have larger spaces available for growing out the fry and eventually rehoming them.

Otherwise, least killifish will also appreciate a densely planted 5-gallon aquarium.

Cherry Shrimp (Neocaridina davidi)

Cherry Shrimp

If you don’t want to have fish in your aquarium, then a shrimp tank is the next best thing. Cherry shrimp are relatively easy to maintain as long as water parameters are kept in check. They bring incredible pops of bright color against a green backdrop!

If you’re lucky, the adult shrimp will start to reproduce and quickly fill the tank on their own, which is good as they can be quite expensive. You may add 3-5 individuals to start.

In addition to cherry shrimp, you may also add orange sakura, yellow shrimp, blue fairy shrimp, and other variations. See this thread for more freshwater shrimp options.

Once added to the tank, ensure that your shrimp are protected from being sucked up by any filters or wavemakers.

If you’ve never kept shrimp before, check out this Reddit thread! Contributor, chaotemagick has created a fabulous infographic explaining how to get started keeping cherry shrimp in your 5-gallon tank. This thread is packed with useful information that you’re bound to find helpful, so do give it a look.

Dwarf Crayfish (Cambarellus spp.)

Dwarf Crayfish

Dwarf crayfish are favorites for stocking nano setups because they are small but pack plenty of personality!

Crayfish can comfortably be kept in a 5-gallon aquarium as long as they are given plenty of hiding places.

When picking a dwarf crayfish species, be sure to choose one of the smaller ones, such as the least dwarf crayfish (Cambarellus diminutus), and not the larger Mexican dwarf crayfish (Cambarellus patzcuarensis) that needs more space.

At most, only two dwarf crayfish should be kept per 5-gallon aquarium. You will also want to check compatibility with fish species if you plan on transferring them to a larger aquarium eventually.

Thai Micro Crab (Limnopilos naiyanetr)

Thai Micro Crab

Thai micro crabs are so small you might not even see them! These crabs aren’t the most obvious choice for a 5-gallon aquarium, but they can bring some life to a small ecosystem.

Thai micro crabs are perfect for nano setups that have lots of hiding places and peaceful fish; this crab species can be quite difficult to find and is often recommended only for experienced nano tank keepers.

Otherwise, they are primarily scavengers and filter feeders that help remove algae and other microorganisms. They easily get along with shrimp and snails but might be eaten by more aggressive, predatory fish.

Smaller Snails

do assassin snails eat shrimp

Aquariums don’t need to be complicated to be beautiful! A simple planted setup with a couple of freshwater snails might be perfect for your home.

Nerite (Nerita spp.) and assassin snails ( Clea helena) are some of the smallest, most manageable snail species available. Nerite snails need brackish conditions to reproduce, which makes population control very easy; assassin snails lay one egg at a time and will go after each other if there is no easier prey available.

Because they’re carnivorous, assassin snails should never be kept with other snail species.


Although your options for fish are limited, 5-gallon aquariums are perfect as planted tanks. There are plenty of plant species that stay relatively small and don’t require much maintenance.

Click here to see some of the best beginner plants for a nano aquarium!

Setting up and maintaining a lovely green aquascape is not as difficult as many aquarists think, and nothing will make your stock happier than a natural environment with plenty of hiding places.

A well-maintained planted tank will brighten up any room and bring a tiny piece of nature into your home. Even in such a limited amount of water, you can set up your own little ecosystem.

One popular method for keeping a small planted tank is the Walstad Method. These systems are self-sustaining, with an abundance of aquatic plants that receive nutrients from snails, shrimp, or fish.

Theoretically, these tanks do not need any maintenance when set up correctly, though some preparation and research will be required beforehand.

Final Thoughts

The best way to stock nano tanks is still the subject of heated debate on many aquarium forums and websites. When picking stock yourself, keep in mind that just because a fish is living doesn’t mean that the fish is thriving.

Be honest with yourself about what’s best for your fish, and remember that understocking is always better than overstocking. Responsibly choosing fish can save you a lot of heartache, trouble, and expense in later stages.

If you still have questions about stocking your 5-gallon aquarium or if you want to share your own experiences with a nano tank setup, be sure to leave a comment below.

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91 thoughts on “Stocking a 5-Gallon Fish Tank: An In-depth Aquarist’s Guide”

  1. I have a 5 gallon tank that I inherited with a black skirt tetra. I’m slowly trying to turn it into a more natural looking planted tank, but wasn’t sure if it’s best to give up the tetra to my local fish store and restock with more suitable fish/shrimp/snails or if I should keep the tetra and add a few more fish, shrimp, or snails.

    • Yes! I would recommend rehoming the tetra. They do best in groups of at least 6 and black skirts are one of the larger species. 5 gallon tanks can definitely still be exciting, though a 10 gallon would open up a lot more fish options if you’re willing to buy a new tank altogether. Otherwise, you’re pretty limited to the species on this list.

  2. I have a planted 5.5G what are some good fish that I can put in, I have years of experience a flat temp. of 80 Fahrenheit and 10 gallons worth of filtration.

  3. I have a 5 gallon tank and I have a glofish shark and two glofish tiger Barb’s in mine with a couple of glofish rocks and decorations. As long as I keep my tank cycled I have not had a problem. Plus they are fun to watch at night under the blue light as everything in my tank glows

  4. Hi I am Very New to this Aquarium Hobby So I really Need Your Help
    So I Got a 6 Gallon Tank Recently Dimensions Are : 15.74Inches x 9.05Inches x 9.84Inches
    and I also Got A Good Internal Filter and the Temperatures are also All right as I Live in India my Water Temperature is around 26-28Celcius.
    And I Wanna Buy A Beautiful Looking And Hardy Fish.
    So can you suggest Me Fish Please
    Which Fish do you Suggest Me?
    And Thx a Lot

    • Hi Prudhvi!
      Your best bet for a hardy, beginner fish in 6 gallons is a betta fish. Everything else is a little more experienced for that tank size.

  5. Hello, I just recently bought a 5 gallon cube tank that I am going to put my betta in. What other fish can I include and how many? Also, what temperature should I have the tank at?

    • Hi Brianna!
      A 5 gallon is good for a betta and 1-2 snails. Some hobbyists have luck with shrimp as well, but if you’re a beginner, I wouldn’t recommend it (those shrimp can really be expensive and sensitive to changes in water parameters!).
      The tank should always be between 77-80 degrees Fahrenheit.

  6. I am about to set up a well planted 5 gallon tank, and I’m wanting to have a betta, 2 amano shrimp, 1 nerite snail, and 1 kuhli loach. Will this work?

    • Hi Jason!
      A 5 gallon planted betta tank will look great and your stocking plan should work for the most part. However, kuhli loaches are pretty active fish and do best when in groups. A 5 gallon tank is simply too small to make your kuhli feel truly at home. Everything else is good, though!

    • Hello Mari,
      I would like to get some advice. After reading this article about setting up 5 gallon tank I made up my mind. I am experienced aquarist. But I never had small aquarium like 22 litre as I am planing to set up. I was thinking to put in, except some live plants and few cherry shrimps, 3-4 female bettas, which I saw in the store. I somehow find aquarium without fish not that interesting, but I would like to have more then 1 fish in it, so I thought female bettas will be more suitable, but only if they can work with cherry shrimps, which I also find attractive and I think instead of snails to put them. Is this a good choice? Will it work? Thank you for your answer.

      • Hello Vladimir!
        A smaller tank isn’t that much more difficult than a larger tank if you’re willing to put in the work, though as you said, you’re that much more limited for what you can do.
        Your plan sounds great, except for the bettas. Unfortunately, with a small tank, you’re going to be limited with fish that you can keep. 3-4 bettas need at least 20 gallons (75.7 L). Betta harems are pretty tricky to set up in the first place and definitely need all the space that they can get for aggression.
        The best choices for your tank would be one male OR one female betta, least killifish, or just invertebrates. Unfortunately, there are not too many species of fish you can keep in that size of a tank. That doesn’t mean that it will be boring, though!

  7. I want to get a 5 gallon tank and stock with shrimp. Can I mix cherry/crystal/ghost shrimp? Also, how many total shrimp should I have in the tank, and is there an ideal amount of each? I also wonder if you know of a good source of information regarding plant planning for the setup I am describing. Thanks!

    • Hi Mat!
      You can mix the ghost shrimp with both cherry and crystal shrimp, however, they have a tendency to eat offspring of other species. Crystal shrimp tend to be much more sensitive to water parameters than cherry or ghost shrimp; their preferred conditions are also slightly different in general, and it’s enough to stress out and even kill your cherries. I would recommend picking one or the other and doing a species-only tank. Remember that species of the same genus can interbreed, so avoid mixing similar shrimp!
      As for how many you can have in a 5 gallon tank, you can have a decent amount of any of them. Because of their high price, hobbyists usually buy 3-5 shrimp and let them breed on their own. As long as your water parameters don’t start to fluctuate and the tank doesn’t look cramped for space, then it is hard to have too many shrimp.

    • Hi Philana!
      Nerite snails are some of the best snails to get for a tank since they need brackish/saltwater to reproduce. This means that you won’t have any problems with them overpopulating your tank. For a 5 gallon, I would get maybe 1-2 nerite snails at the most. You want there to be enough natural algae for each one to have.
      Unfortunately, 5 gallons isn’t too big to begin with, and being tall will make stocking even more difficult. The best stocking would probably be one betta fish with one nerite snail; being a tall tank, make sure that your betta is able to swim to the surface of the water without getting tired. If you see your fish struggling, you might need to add plants/other resting spots near the top.
      The other option would be to make this tank a shrimp-dedicated setup. There are several types of shrimp, like Amano and cherry, that can completely bring an aquarium to life! You can also add live plants and watch the shrimp graze on algae. Though small, they’re definitely an underrated addition.

      • I was wondering in a 5 gallon tank instead of just having only one fish like a betta is there anyway I could have more than one fish in a tank and what fish would that be if possible?

        • Hi Johnie!
          5 gallons is, unfortunately, not a lot of space for fish and the betta/shrimp/plant combination is always the most recommended setup. That doesn’t mean that you can’t have a showstopping tank though!
          Some fish you can keep in a 5 gallon are endler’s, chilli rasboras, and scarlet badis; if you really want to test your aquarium skills, you can always make your 5 gallon a mini saltwater reef. Remember that your water parameters will fluctuate much more than a larger tank would and to make sure that the fish you get don’t need to be in larger schools.

  8. I’m looking to start a 5 gallon freshwater aquarium. It will mostly be shrimp. But, I would like to add either a dwarf crayfish, micro or pom pom crabs, and or nerite snails. Is there a combination where I can add two or more with the shrimp? I plan on having plenty of plants and hiding areas.

    • Hi Brian,
      5 gallons isn’t a whole lot of space to play with, but some people make really beautiful nano systems. I think the key to these tanks is simplicity but with diversity. I personally have not had good experience with crayfish, so I am a little biased and tend to favor shrimp-only planted nanos. A lot of people like to keep cherry shrimp with pom pom crabs, though there is always the chance that your crab could go for one of the shrimp. For a 5 gallon tank, I would go for maybe 2 crabs and maybe 2-3 shrimp. Honestly, snails will probably come in on any plants you buy anyway, so I think that space would be more interesting with crabs and shrimp instead.
      I hope this helped!
      Happy crab-keeping!

  9. Hey on the dwarf crayfish you say they’re suitable for a 5 gallon but when I look on the provided caresheet, it says I need an 8 gallon. I’m very confused due to this. Could someone clear this up?

    • Hi Lillie,

      It is a little confusing, but the smallest crayfish species, such as cajun dwarf crayfish, are suitable for 5 gallons and slightly larger ones like the CPO crayfish need a little more room, that’s why it’s set to 8. So the range is 5-10 gallons with each tank minimum being dependent on the species you’re looking to buy. Sorry that is a little confusing! If you have questions about a specific species, I can help even more.

      Happy crayfish keeping!

  10. I have a five-gallon tank that I am wanting to use for betta. I have read else wear that you can have snails and betta together, and the snails help with bio cycling. Would this work?

    • Hello! It’s true that you can keep Bettas with some types of snails. In a five gallon you could consider a nerite snail or an assassin snail, since their bioload is not so big. The snail won’t help with cycling nor will it keep your tank clean like some aquarists think, but they’re fun to watch doing their thing scraping the tank walls 🙂

  11. Hi- I have a 5 gallon marineland tank. I currently have an Amano shrimp and an olive horned Nerite snail in there. I have 2 Marimo balls and 3 other plants in the tank. Can you recommend some fish that would be good in this particular set up. I love the nano fish and have thought about a betta- but I would like some other ideas. I want something active and colorful. Thanks in advance.

    • Hello! What I would do personally is actually some Cambarellus diminutus, texanus or one of the other mini species. They are actually more fun than a fish would be in many cases with their silly antics. Additionally, aside from the species on this list there are no fish that can be kept in a tank this size in my opinion. It’s really only Bettas.

      Good luck!

  12. Hello Mari. Thank you for this very insightful article. I currently have a 5 gallon with a RCS, nerite snail and ramshorn snail, but am planning to add 2-3 least killifish and some Thai micro crab. How much of these animals on the list can I ideally stock while keeping all of the animals healthy and thriving? I wanted to ideally add more RCS as well and possibly the dwarf crayfish. Thank you again!

    • Hi! I think with your current plan you might be overstocking the tank a little. I would skip the fish here and stock it with RCS, the crabs and the snails. I’d skip the dwarf crays as well in this case or swap the crabs for crays. Don’t worry about the tank being boring; with this stock it’ll be a joy to watch! 5 gallons is just really tiny and it”s best not to overdo things.

      Good luck 🙂

      • Hi again! I didn’t mention it beforehand, but does it make a difference if my tank is heavily planted with a filter (the one that comes with the Fluval Spec V to be exact)? Asking because I’m really looking forward to the killifish as an addition to the tank (around 3-4), in hopes of stocking the other animals around them. If my nerite snail moves out could that possibly give more room for the micros along with the RCS?

        • I was already factoring in a filter, since that’s a must for all aquariums. Plants help but you still really have to watch your stocking plan since things can go south so quickly in small set-ups. What you can do is go with the killies and the RCS, but if that’s what you want then I’d skip the rest. Snails especially produce quite a bit of waste.

          If you have room you can always set up another 5 gal for the snails and crabs or crayfish, maintaining two doesn’t take much more work than one.

          Hope that helps! 🙂 Good luck, sounds like a fun project you’re working on here.

        • If you plan to keep Least Killifish with RCS, you’ll need to HEAVILY plant your tank to create hiding spaces for your RCS or the fish will gang up to bully and eat them. Happened to me after I removed plants.

          • Really?! I wouldn’t expect such small fish to go at the RCS so hard, especially considering the fact that their larger guppy cousins do relatively okay with them. Good to know 🙂

  13. hey its me again, I just wanted to say thank you so much for all the help you have given me and im here also to report that i have finally rehomed my guppies and Bristle nose. Also just one last favor that i need, i was wondering if you could maybe do a caresheet for the killifish and also what is in your opinion the best tank to get. Thank you!!!ga

    • Hey! Thank you for the update, I love getting them especially if they’re positive! As for Heterandria formosa, I don’t have much personal experience with them so I’m not sure if I’m the right person to do a caresheet on them, but there is one on Seriously Fish that seems pretty good 🙂

      As for tanks, it doesn’t matter too much and totally depends on what you want from it – although I do recommend a rectangular rather than a square one if you’re interested in keeping active species like these “killifish”. They like having some swimming room.

      Good luck!

  14. Also, if I get 2 to 3 killifish how many shrimp or cray fish can I put in as well. What other kinds of shrimp can I put in that are ok but attractive. Thank you

    • If you get 2-3 least killifish (Heterandria formosa, they’re actually tiny livebearers that somehow got named “killifish”), I’d recommend going for shrimp instead of crayfish as these have a lower bioload. It’s easy to overstock these tanks! Since you’re a beginner, I’d try Neocaridina shrimp. They come in all sorts of funky colors (red/yellow/green/blue/black/brown/orange), all of which have the same care requirements. You can have a look at the cherry shrimp caresheet if you’re interested. You can start out with a colony of 5-10, there isn’t really a set number for them as they produce so little waste. If you feel like they’re breeding too much, just sell or give away a few! Hope that helps 🙂

      • Not really. Maybe a tiny bit, since plant leaves die and decompose, but the effect of that should be pretty minimal because plants also make themselves useful by absorbing harmful substances 🙂

    • Hi! I can totally understand being confused. Here comes a wall of text:

      You do water changes based on your water values. Have you gotten a liquid aquarium test kit yet? It’s an absolutely crucial part of fishkeeping (don’t get the cheaper strips, they’re inaccurate). Try the API Master Test Kit. You also need it to cycle your aquarium (if you haven’t done that yet, go to that link first and forget everything else until it’s done).

      When you’re still figuring out how often to change the water, you just do water tests every other day or so and look at your nitrates. Those are a good indicator of how “dirty” your tank is. If they get above 15-ish, do a water change and see how the nitrates respond. Try to keep them at 10 or under. After a few weeks you should start seeing the pattern and you’ll know when to do a water change. Does that make sense? 🙂 it all depends on your stock, how often you feed, water temperature, plants, so there is no set schedule and you’ll have to figure it out yourself with the help of your test kit.

  15. I want to do an elaborate nana (5 gallon) aquascape, you didn’t really go into to much depth on the live plants, I am very beginner enthusiast when it comes to aquatic and semi-aquatic plants, however have enjoyed my massive jungle that ranges from air-plants to ground, a very small high humidity terrarium, I kinda began a couple of 10 gallon fish aquariums to establish better water for watering them, I use the water from the fish tanks (it’s chlorine free and pre low level fertilized, so much easier to “feed plants” this way. I have a 5 gallon aquarium with 5 small “feeder fish” I am not sure of species the sign on them said White Clouds but the store owner said that they are captive breed guppy/endlers I know that they were in really poor health when I got them but seem to be healthy and happy now, but they are going into the 10 gallon aquarium, the 10 gallon aquarium has 2 Neon Dwarf Grourmis and 3 dwarf frogs, the Neon Dwarfs are being moved to a 29 gallon aquarium, all tanks have hornwart and the 2 **5 gallon aquariums have Marino moss balls and I have ordered grass and baby tears, in both sizes (seeds).

    • Hi! Seems like you are definitely on a roll with the aquariums. If you want more info about plants I definitely have plenty – this article is strictly about fish hence the lack of plant info. The list of nano plants might come in handy for you.

      I do see a few things about the stock you mention that I’d like to address – the guppies/endlers or white clouds need an aquarium of at least 15-20 gallons, preferably more. They are active swimmers. Your dwarf frogs need a little more room as well. The absolute minimum for them is 15 gallons (as discussed in the dwarf frog caresheet) and they are best kept in a single-species setup so they aren’t bothered by their tankmates.

      Good luck with your aquariums and houseplants! 🙂

  16. Hey aquariadise your articles are a real boon to beginners and experts alike 🙂
    I got a 3 gallon fish bowl with 4 Mollies in it(ik I need a larger aquarium but I don’t have the space for now ) what plants do you recommend? I’m just a beginner and I don’t really know much about aquarium plants
    Thank you 🙂

    • Hello!

      I’d recommend plants from the 8 easy aquarium plants list, those are all suitable for beginners. But you do REALLY need a larger aquarium soon. 10 times as large actually – as you can read in the molly caresheet here the minimum tank size for them is 90cm which comes down to around 30 gallons. If you don’t think you’ll be able to provide that soon I really recommend you rehome the fish to someone who can, as they might not live a long life in such a tiny setup. Once you have rehomed them you can get some dwarf shrimp (your only option in a 3 gal).

      Good luck!

    • I wouldn’t do that. In a tank that tiny I’d definitely stick to a maximum of 1 species. They’ll be so cramped I suspect the Betta might turn on his tankmates!

      • Hi, I was thinking of setting up a five gallon with maybe some shrimp, small fish etc.
        And I was wondering how many fish would you suggest having in a five gallon?

        • Hello! All the information you need is in the article. There are only two fish species I would recommend for a 5 gallon: either a single male or female Betta splendens or 2-3x least killifish (Heterandria formosa). You can add some shrimp if you go for the Heterandrias, with Bettas it might not be a success.

          This might be less stock than you would have wanted for your tank but if you add more fish or other species you will run into problems. 5 gal is extremely tiny and just not suitable for most species. Good luck!

      • By chance, do you know the minimum number of least killifish one can have in a tank without the fishes being uncomfortable in the environment? the question probably doesn’t make sense . . .let’s see. . .
        For example, I have a 10 gallon tank with 10 chilli rasboras, and was given 3 male least killifish from a co-worker. Should I be worried that I don’t have enough least killifishes for them to be comfortable in the tank? The Least killifishes I have seem to socialize (in this case, shoal) with the chili rasboras, but I’m not sure if I should add more least killifishes to make them more comfortable.

        • Hello! That’s a good question, but I think 3 is okay although I’m by no means an expert on them. I’ve read they can be kept in pairs or trios. If they seem to be shoaling with the rasboras and don’t seem skittish or stressed I’d leave it at this because you’re already pushing the stock with your current tank size.

          Good luck! 🙂

  17. Hi! I recently set up a planted 5 gallon, and it’s the process of cycling. I was hoping to add some RCS, but I’d love to introduce a tiny fish or two as well, especially since the shrimp need a more mature tank. I’m not sure if my local pet store stocks killifish — are there any other fish you could recommend? I currently have a betta in an 8.5, but I learned the hard way not to try to stock a betta and shrimp in the same tank. Are there any similar species that you would recommend? I have no problem with making it a shrimp-only breeding tank, but if there’s any way I can get a fish or two in there so that I can put something in a little earlier than the shrimp, that would be awesome.

    • Hi! That sounds like a nice little tank. I definitely agree RCS and Bettas are a recipe for disaster. As for least killifish, they aren’t actually real killies but tiny little livebearers. I doubt most pet stores stock them but you can always try looking for them online. They (along with a single Betta) are unfortunately the only fish option I’d recommend for a 5 gallon, and even those I’d personally keep in a larger setup. I know the internet is full of articles about fish that are “suitable for 5 gallon tanks” but I strongly recommend you stick with just the RCS and maybe 2x Heterandria formosa. A 5 gallon is TINY and things can just so easily end up going wrong if you’re not careful.

      As can be read in the article you do have a few fun invert options. The tiniest crayfish species (Cambarellus diminutus) would work in a 5 gal and they’re just as feisty as large crays; they leave shrimp alone. A few small snails can also work! Good luck 🙂

  18. Also what size of tank that is resonable has a bigger variety of marine life that I can have (up to 15 or is 15 a bit too big)?

    • I’m not an expert on marine tanks at all but I do know they need to be even larger than freshwater, as many species get quite big. 15 gallons is considered a nano tank in this area as far as I know and your options are likely limited to just a few species. If you want a larger variety to choose from you’ll probably have to think closer to 150 gallons!

    • Hello. As you can read in the article that is unfortunately not okay at all, neither of those do well in a 5 gallon. They may seem perfectly fine but they aren’t. Please rehome them as soon as possible and then look into stocking your tank with one of the species on this list if you’d like.

  19. What can I keep with crystal black shrimp? Im considering buying 10-20 of them and also a dwarf crayfish in a 5 gallon tank or is that too filling for the tank?

    • Hi! As long as you go for one of the tinier dwarf crayfish types that should be fine. So no Cambarellus patzcuarensis – Cambarellus diminutus is better. 🙂

  20. Hi…I’m just getting back into fish and I’m actually looking to stock a 7-gallon tank. I was thinking about a Betta, 2 pygmy corys (I know you say they do better in a larger tank… but I was hoping they’d do well in 7 gallons) and 2 snails. Do you think that would be too much?

    • Hi,

      I’d stick to just the betta and snails (Nerite snails would be great). You can also try dwarf shrimp if your betta isn’t the nippy type. The pygmy Corydoras are really not suitable for a 7 gallon, partly because they should be kept in groups. 2 is not going to cut it, you need to have at least 8 or so or they will be stressed and unhappy. With just the betta the tank will still be lively and fun, so no worries! 🙂

  21. I’m setting up a 5 gal aquaponics system. So there will be more intense filtering of the nitrates than with a typical aquarium. My plan was to go with 7 neons and a few cherry shrimp. Will the addition of the aquaponics system as a cleaning element for the nitrates allow me to increase my stock levels, or not.

    • Hello! I guess it allows you to slightly increase your stock level but unfortunately neons are still not an option. They are just too big for such a tiny tank and need much more swimming room to be happy. I’d just stick to one of the species on this list! Good luck 🙂

  22. I have 5 gallon aquarium and I have 1 shark and 3 gold fish and they lived happily for 3 months and then I bought another shark and the next day my 2 goldfish died. Can you explain why? Is there low oxygen level?

    • As you can read in the article, none of these fish are suitable for a 5 gallon aquarium. They all grow MUCH too large and are not compatible. Please rehome the remaining shark as soon as possible as it needs a way, way bigger aquarium. The goldfish likely died of stress and bad water values.

      Sorry I don’t have better news! Dwarf shrimp like cherry shrimp would be a better choice for this tank.

    • Hi! That should work. I’m not a huge fan of ghost shrimp with Bettas but it should probably work with a short-finned female.

      • Okay great! Thank you. Also do you have any other plant recommendations? I’m going to put some moss balls in there, but wanted to put a live plant or two. Something low maintenance preferably.

  23. I have a 5 gallon tank with a very senior Betta, I thought it needed life so I added some shrimp, which he ate. Then I tried 2 mystery snails. What a horrible idea! They made such a freaking mess! If you have a 5 gallon tank, just keep it simple. I decorated with live plants to make it more enjoyable for me. If my old man fish ever dies, I’d like some crabs and shrimp in there. This is about the only site I’ve found that gave proper advice. And I’m saying this from experience.

    • Yeah, mystery snails grow so large they are really only suitable for tanks of 15 gallons and up! Glad the article was helpful 🙂

  24. Hey, I’m planning on putting about 10 red cherry shrimp and 2 amano shrimp in a 5 gallon rectangular planted tank. I’m not sure if the shrimp will do okay with the betta present…any advice?

    • Hi! I can’t really tell you whether it will work because not all bettas are the same – some will hunt down and kill any shrimp right away, others leave them alone. In any case, make sure you have a plan B for the shrimp in case things go south!

  25. I have a 6.6 gallon tank and was planning on putting one male betta, 5-10 cherry shrimp, and 4-7 neon tetras in it. Plus live plants, and one artificial treasure chest with a whole in it. Would that work?

    • As you can read in the article that would unfortunately not work! Neon tetras are too large and active for a 6.6 gallon. 4-7 is also too little for a proper school and neons make bad betta tankmates due to their bright colors. With the Betta and the shrimp your tank is pretty much maxed out, so I’d definitely stick to just those two.

      Good luck 🙂

  26. Hi! I happened to come across this article and wondered if I had a nice community aquarium. What do you think?
    I was thinking maybe 6 Glofish Danios, 5 ghost shrimp, some snails, and African Dwarf Frogs! (:

    • As discussed in the article, tanks under 5 gallons are unsuitable for any fish whatsoever and even 5 gallon setups can only sustain a handful of species. Of the species you mention, only the snails would work 100% – even for ghost shrimp, 3.5 gallons is on the small side. Please, no vertebrates – only inverts like dwarf shrimp and snails.

  27. I have spent the last 3 days updating my knowledge about aquariums in general and then researching information about 5G tanks and was ready to throw in the towel until I found your site. Finally, a person with experience and sound advice. Thank you.

    I do have a couple of questions about the number of creatures I can have in this 5G nano. Suppose I selected one dwarf crayfish, 5 cherry shrimp, and a few snails, could I have one fish? Not a beta or a killifish. Although I have no experience with killifish, they just don’t look interesting. Any other suggestions?

    Also, can I mix different species of shrimp in the same tank.


    • So glad this article was helpful to you! To answer your questions:

      1. Aside from the species on this list, I cannot think of any fish that would work in a 5 gal, sorry! They all grow too large or need more swimming space. Single fish of many of the tiny species, such as microrasbora, would fit in a 5 gal but they need to be kept in schools and therefore require more space. I personally rule out fish completely when stocking a 5 gal and just stick to inverts. A crayfish, cherry shrimp and some snails would be great. The cray should provide all the personality you need!

      2. You can mix different species of shrimp in the same tank, but keep in mind that if you keep multiple color varieties of the same species together their young will revert back to a brownish wild color. A compatibility chart can be found here.

      I hope that helps, good luck!

      • Thanks Mari. What if I went one size up to a 9 gal (34 l) tank. Could I keep a couple of fish with the inverts? If so, what do you recommend. Perhaps they could help with the shrimp “problem”, i.e., if my shrimp do have young I’m not sure what to do with them and perhaps the fish could provide that solution. That is, unless they decide that the adults are also rather tasty.


        • I wouldn’t worry about your shrimp multiplying, I’ve found that the population pretty much stabilizes after a while.

          As discussed in the article, there are a few fish you can keep in a 9 gal: a pair of least killifish would work, as would a betta (though the latter might be a little too effective when it comes to dealing with “shrimp problems”). For more stocking options you could also have a look at this article, though keep in mind that because a 9 gallon is still really small you should only go for the smallest, most inactive species. Hara jerdoni would be a cool option if you can find them.

  28. I have a 5 gallon tank with a very senior beta, I thought it needed life so I added some shrimp, which he ate. Then I tried 2 mystery snails. What a horrible idea! They made such a freaking mess! If you have a 5 gallon tank, just keep it simple. I decorated with live plants to make it more enjoyable for me. If my old man fish ever dies, I’d like some crabs and shrimp in there. This is about the only site I’ve found that gave proper advice. And I’m saying this from experience.

  29. I just moved and my old tank was a 75 gal with 24 small fish in it (like the size of neon tetras and cherry barbs) it was a planted tank as well. since we moved I set up two 5 gal tanks (well 1 is a 5.5 but you get it lol) one of the tanks is your average 5.5 gal and the other is the Fluval Spec tank so its longer than it is wider, I have 9-10 fish in each tank because all my Local fish stores wouldn’t take my fish (missing a good offer for free lol) so I have them like I said 9-10 in each, with my other tank/tanks I was really good on keeping it clean and the plants and some of the fish helped me keep it clean to, so will these two 5 gallon tanks be ok with the very small 9-10 fish in them? and also im good about keeping required PH levels and average cleanliness of the tanks anyway but will the fish be ok, they seem to get along and be swimming calmly just acting normal. ???

    • Hi! Unfortunately neon tetra and cherry barb sized fish don’t classify as small fish – schooling fish are very active and need a lot more space than 5 gallons. If the aquarium store won’t take them, try rehoming them to other aquarists! The current situation is not ideal.

      Good luck!

  30. Hi Mari–

    Thanks for all the info! Your dwarf crayfish care sheet recommends an 8-gallon tank. Two in a 5-gallon tank seems much tighter. Does it just depend on planting & personality?

    • Nope, it’s actually specified in the caresheet! The smallest crayfish species such as Cajun dwarf crayfish are suitable for 5 gallons and slightly larger ones like the CPO crayfish needs a little more, that’s why it’s set to 8. I’ve made a note in the article as well, though, as I’ve gotten multiple questions about it now. 🙂

  31. I agree with most of this. Might I suggest that the dwarf livebearer/dwarf killifish with a tank of thick Najas g. work fine with a 5 gallon?


    • I was kind of doubtful about adding these, but since I’ve listed the least killifish as suitable for 5 gallons elsewhere on Aquariadise I’ll add that one to the article 🙂


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