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Caresheet: Assassin snail | Clea helena

Last Updated March 23, 2020
clea helena

Even the most careful aquarium hobbyist can end up with a pest snail infestation in their tank. In the search for a quick solution, aquarists often turn to fish that eat snails, like puffers or clown loaches. These may initially be an easy fix, but most don’t consider tank size and which fish they can actually accommodate in the long run, which leads to even more problems. Luckily, there is another option: assassin snails.

Keep reading for more information on assassin snail care and their effectiveness when dealing with snail infestations in your tank!

Minimum tank size5 gal (19 L)
TemperamentModerate
DietCarnivore
Temperature75-80 °F/24-26.5 °C
pH7.5-8

Name

Clea helena (more appropriately named Anatome helena), is commonly called the assassin snail or the bumblebee snail.

Natural habitat

The freshwater assassin snail is typically found throughout southeast Asia, ranging from Malaysia to Thailand. They are also found on the island of Sumatra in Lake Toba. Assassin snails do not have a preferred body of water–they are found in many types of freshwater streams, ponds, and smaller ditches–but favor a soft substrate to bury themselves in. As a small carnivorous snail species, assassin snails hide until food is sensed and don’t tend to feed on any plants around them. Usually, these snails are least active around midday but will emerge specifically to eat.

Because of their growing popularity in the aquarium trade, the assassin snail has become an invasive species and is being discovered in many new locations. Their increasing populations may come to threaten many other species of freshwater snail because of the external predation.

Assassin Snail Care Guide

Identification

Their conical, yellow, and dark brown striped shell makes the assassin snail an attractive small addition to any aquarium and earns them the bumblebee name. Occasionally, their shell may lack stripes, but this is rare. They can grow to a maximum size of around 1.25 inches (3.2 cm), although this seems to vary depending on the amount of food available and size of the aquarium. Because of this, the maximum size of assassins in the wild is often larger.

Like many other snail species, the assassin snail uses a siphon that can usually be seen sticking out of the shell to breathe. However, they do not directly breathe air like many other snails. They have an operculum that keeps predators out of their shells when they want to retract their ‘foot.’

Assassin snails are not a hermaphroditic species, so telling males and females apart is not really possible. If wanting to breed assassins, make sure to get larger groups so there is a good chance you get both female and male snails for your tank.

Assassin snail requirements

Although they don’t really group together in a tank, keeping at least 3-4 assassin snails is usually recommended for any aquarium setup. There seems to be a bit of confusion about the minimum tank size for them, but 10 gallons (38L) should definitely be enough for a group that size with some room for additional fish! Assassin snails are very easy to care for and will thrive in any mature tank with stable water parameters. Just don’t get more than your tank size can handle.

This is also one of the few snails that you don’t have to worry about your plants getting eaten, as greens are not part of their natural diet! This makes assassin snails ideal for any small planted aquarium with community fish that won’t try to pick at them. It is also not recommended to knowingly house assassins with other snails, especially their favorite treats: trumpet snails (Melanoides tuberculata)and ramshorn snails (Planorbarius corneus).

Because assassin snails naturally bury themselves and wait for their prey to appear, a sand substrate is preferred, although it’s not a must. The water should ideally not be too soft, as this could lead to deterioration of the shell. As with all tropical fish and invertebrates, the aquarium should be properly filtered, heated, fully cycled, and free of ammonia and nitrites.

How long do assassin snails live for?

As with any invertebrate, any trace of copper in your tank will prove to be fatal for your assassin snail, any eggs that may have been laid, and for any plants. If there is not enough calcium in your aquarium, your assassin snails will also suffer. Unlike hermit crabs, they grow their own shell and require calcium to do so. While their diet, that should include a wide variety of food, will provide some of the nutrients they need, you can also test your water for calcium levels and dose accordingly if needed.

As long as all water parameters and nutrient levels remain stable, you should have no problem keeping your assassin snails alive for a couple of years with minimal care.

Assassin snail tankmates

If you’re thinking about introducing assassin snails into your aquarium, keep in mind that they don’t just eat pest snails. Although not all sources agree on whether they will also devour ornamental nerite snails and even large mystery snails, you should definitely assume they will and avoid keeping them together in your tank. In fact, assassin snails will eat about any type of food that smells appealing in the water column: planaria, fish eggs, and according to some aquarists, even the occasional dwarf shrimp fry.

This means that if you’re breeding your fish or shrimp and want to avoid any risks, you may want to skip assassin snails. Larger tankmates that require the same water values are fine, as long as they’re not snail-eating fish. Good compatible fish are guppies, small tetras, danios, and less aggressive barbs. Loaches and other bottom-feeding fish should especially be avoided as snails are their favorite snack!

Popular aquarium setups involve a species only tank, with an assortment of plants and a group of assassin snails bringing color and excitement to the bottom of the tank. Other than for a display tank, these snails can also be fed to larger fish. Tanks with just assassins are especially appealing as you can specifically monitor their diet and the food they eat, making sure your larger fish get a quality meal!

Assassin snail diet

As mentioned before, assassin snails do not strictly feed on just other snails. While they can wipe out entire populations of pond snails, ramshorn snails, and trumpet snails, they are opportunists that will eat anything that makes its way to the bottom of your tank. This means live prey, deceased tankmates, commercial fish foods, and frozen foods are viable meal options to supplement in your tank.

To feed a steady supply of assassin snails once the initial pest population is gone, you can ask your local aquarium store for smaller snails or breed snails in a small separate tank as described here. However, there is no need to worry if you do ever (temporarily) run out. Feeding your assassins other protein-rich foods, such as bloodworms or brine shrimp, is fine as well!

Assassin snail behavior

Although they will quickly flock to any food that is traceable through the water, assassin snail behavior is very different from that of most herbivorous snails. They don’t move around foraging and grazing on the sides of the tank; their hunting process is quite calculated and interesting to watch!

When they’re hunting for live snails, assassin snails will bury themselves into the substrate whenever possible and wait with just their proboscis (feeding tube) sticking out. When an unsuspecting victim gets close enough to assassinate, they emerge and start to feed. If there is no sand substrate available to bury in, assassin snails will often actively move around the aquarium while searching for other snails to devour. However, this is most likely very stressful for your snails as they have nowhere to hide; it is always recommended to have a substrate or plants for your assassins to hide in!

Breeding assassin snails

Fortunately, while breeding assassin snails is not very difficult, it’s not as easy as breeding pest snails. That would make for two snail infestations! If you do end up with more assassins than you can house after a while, it’s usually not too difficult to find another aquarist or aquarium store willing to take a few for a snail infestation in their own tank.

As mentioned before, assassin snails are not hermaphrodites where both sexes can reproduce. Instead, only the female can reproduce, which means a lot less offspring than other types of snails. Because the two snails look exactly the same, get a big enough group to have a good chance of introducing both sexes into your tank.

As long as there are plenty of snails or other nutrient and protein rich foods available, the assassin snails in your tank will take it from there. The male and female assassin snail will connect for up to 12 hours during this time. You should then soon see light colored, square shaped eggs appear that should hatch in about a month’s time. After hiding for a while among plants and in the substrate, the baby assassin snails will join the adults during feeding time in about six months.

Assassin Snail - Clea Helena

Buying assassin snails

When buying assassin snails, make sure to look for snails that are actively moving around, eating, or stalking prey throughout the aquarium. If the operculum is closed, there may be something wrong with the snail. A flaky looking or deteriorating shell is a sign of calcium deficiency, which may be too late to reverse. If you’re ordering assassin snails online, be sure to look for a trustworthy seller with plenty of good reviews like InvertObsession!

When introducing your snails into their new tank, make sure you acclimate them properly so they can slowly adapt to the different water values just as you would with other fish and invertebrates. Skipping this step means a lot of stress for the snails, which can unfortunately sometimes be fatal!

Conclusion

Although assassin snails do a great job at keeping aquariums snail free, their striking stripes and interesting feeding behavior also make them a great addition to tanks without a snail problem as well. They are fun to watch when hunting and do well in a wide range of water conditions!

If you have any more questions about keeping assassin snails or want to share your experiences with them in your aquarium, make sure to leave a comment below. Happy snail keeping!

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23 Comments

  • Reply Ynot February 8, 2019 at 3:55 am

    How often do / should Assasins eat? I’ve been acclimating and studying 5 of them in an isolated in-aquarium specimen box: aerated, water changed daily, with 3 Pond Snails per Assasin who are fed blanched lettuce. It has been a week and no signs of empty shells. If anything, I’ve seen several times where the pond snails crawl completely over top of the assassins, or congregate as a group on top of one of the Assasin’s shells for a while. A couple of times a pond snail has gone nose to nose with us our son, only to have the assassin pull it’s proboscis back, and either retreat, or steer around the pond snail. Today, just to see if something else would happen, I placed a Cichlid food pallet in the isolation tank (it contains a high quantity of salmon and shrimp). The pond snails loved it and immediately surrounded it. The other assassins have ignored it, with one cruising past it but paying no mind. Is it normal for Assassins to wait so long between eating, or do I have the only group of vegetarian assassins in the Midwest?

    • Reply Mari February 8, 2019 at 6:16 pm

      Hi,

      Oh dear, vegan assassin snails! In all seriousness, I’ve never studied this to the degree that you’re doing now and as such I haven’t a clue how long they go without eating while they’re acclimating. Honestly I’d just leave things be and not worry too much; as long as your water quality is good and you’re following all of the assassins’ care guidelines then it should all turn out fine. Maybe they’ll start eating in the specimen box, maybe they’ll wait until they’re released into the main tank.

      Good luck, I hope it all goes well!

  • Reply Emily H. November 5, 2018 at 1:11 am

    Are these great for baby betta?

    • Reply Mari November 5, 2018 at 1:32 pm

      In what sense? They can be kept with Bettas usually, yes, but they wouldn’t have any specific advantages for your fish.

  • Reply Paulo Lisboa March 16, 2018 at 7:13 pm

    I’ve got a pair of big Neritina Pulligera. Will they be in risk if I join a pair of assassin killers?

    • Reply Mari March 17, 2018 at 11:47 am

      There’s no way to be sure whether they’ll be eaten of not, but I personally wouldn’t take the risk with such beautiful snails!

  • Reply Gaby October 28, 2017 at 10:23 pm

    Hi was wondering I have 5 guppies in a 5 gallon tank with a small bristle nose and I reacently added 3 assasin snails might this be too much because I asked the people in my local fish farm and they said not to keep more than 8 guppies thanks
    (Ps their doing very well I’m just curious)

    • Reply Mari October 28, 2017 at 10:28 pm

      Hi! Unfortunately the minimum tank size for guppies is 15 gallons. The minimum tank size for a bristlenose pleco is 30 gallons. The only thing that can actually be kept in your tank are the assassin snails; I strongly urge you to rehome the fish as soon as possible because a tank this small will not be able to handle their bioload in the long run and their lives are in danger.

      Please do not believe anyone who says there are plenty of fish species that can be kept in a 5 gallon, including your fish store. For some reason people believe fish will be happy in these tiny tanks but they won’t. I have an article on stocking a 5 gallon here and the species listed there are the ONLY ones I recommend for a 5 gal. As you can see there are only 2 fish on the list. A good stock for your tank would be the assassin snails and a pair of small dwarf crayfish like Cambarellus diminutus; they are very fun to keep and small enough to live a happy life in there.

      Sorry about the long answer – I just really hope you’ll take my advice before things go fatally wrong! Good luck with the assassins 🙂

  • Reply Kimbelry July 26, 2017 at 7:11 pm

    can i use assassin snails in my back yard pond? i am infested with pond snails!!!

    • Reply Mari July 28, 2017 at 6:22 pm

      They are tropical snails so only if you live in a tropical climate! 🙂

  • Reply Dave March 14, 2017 at 10:04 pm

    They will definitely kill large mystery snails. I got a nice big one and added it to my aquarium hoping he was big enough to resist the nerites and he was dead within hours. 🙁

    • Reply Mari March 16, 2017 at 9:12 am

      Oh, sorry to hear that 🙁 but thanks for sharing.

  • Reply Vicki January 23, 2017 at 5:27 am

    I have a 5-gallon tank. Would 5 Assassin snails be too many for my tank size? Also, do Assassin snails eat the egg sacks or just the newly hatched snails? Thanks so much!

    • Reply Mari January 26, 2017 at 11:28 am

      5 might be a bit much, 2 would be fine as well for snail extermination! They eat all kinds of organic material so they might go for the egg sacs as well, yes. 🙂

  • Reply Denny September 24, 2015 at 8:44 am

    Hello . Loved your post. please tell me, do you know if assassin snails can be fed with garden snails? Will it ruin the tank water?

    • Reply Mari September 24, 2015 at 8:57 am

      Hi! I don’t think feeding assassin snails with garden snails is a good idea, they contain all sorts of stuff the assassins won’t be used to! If you’re having trouble finding pest aqurium snails to feed them, try asking around at pet- and aquarium stores 🙂

    • Reply Ginger October 3, 2015 at 3:04 am

      hi um if you need snails please email me at [email protected] i have so many ramhorns they are extremely free

  • Reply Psybur September 14, 2015 at 1:37 am

    What the hell is that noise in the background of the video?

    • Reply Mari September 15, 2015 at 10:06 pm

      It’s not my video so I’m not sure actually, sorry! I tested it before posting and I didn’t notice anything too strange/excessively loud… it just sounds like a machine running in the background to me. Or are you hearing something completely different?!

      • Reply Psybur September 16, 2015 at 4:19 am

        Sorry, I didn’t mean to come off so brusque. I was just saying it regularly (I swear a lot, sorry). I just found it humorous that it was happening.

        • Reply Mari September 16, 2015 at 9:45 am

          No problem haha! After the incident where I didn’t notice the reflection of a naked guy’s chest in a video of a rosetail betta I was just worried maybe I missed a strange or inappropriate sound…

          • Psybur September 18, 2015 at 7:23 am

            ROFL, he’s probably in the background murmuring, ‘I’m too sexy for my shirt. . . ‘ while that’s going on! That’s hilarious; is that video still there?

          • Mari September 18, 2015 at 4:29 pm

            It’s not in the article any more, but I had a look on Youtube for you and managed to find it again here… I hadn’t even noticed it until a commenter pointed it out haha. 🙁

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