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Assassin Snails – Killer Snails for Your Aquarium

In my first blog, I talked about why the Zebra Loach (Botia striata) is well suited for smaller aquariums, and why it was certainly a more sensible choice for snail control than its larger cousin, the Clown Loach. The Zebra Loach is one of the most under rated of the snail eating Botia, in my opinion. But what if you have a planted aquarium and you’re keeping small shrimp? Zebra Loaches may very well eat them! Or what if you have a small tank, but don’t have room to house 4 or 5 of these fish? Well, I think there may be something that is just as effective, does not appear to want to eat the little shrimp, and won’t take up a lot of room. A somewhat new introduction into the hobby called the Assassin Snail.

The Assassin Snail (Clea helena or Clea Anentome helena) comes from lakes and ponds in Southeast Asia, where it feeds on decaying protein, worms, and other snails. That’s right, a snail that eats other snails. Voracious little predators, the Assassin Snail has an attractive yellow shell with a spiraling brown stripe wrapped around it. While they do have an appetite for snails, predation does not occur within their own species. This allows several individuals can be kept in a single small aquarium. At an adult length of just under an inch, a 10 gallon aquarium could easily house a dozen of these snails. They are pretty durable and can take a wide range of water chemistry, as long as it does not fluctuate greatly. While preferring a pH of 7.0 or 7.2, they can tolerate a range from slightly above 6 to about 8.2. Water hardness, can also be somewhat flexible. Reports of keeping them in water with GH values of 5 and a dKH of 1 seem to be pretty standard. Fine gravel or sand is always preferred, but not a necessity. If you do have fine substrate, these little guys will burrow and crawl through the substrate in search of food.

Assassin Snails are known to be extremely active. The idea that snails are slow and plodding is definitely challenged by this gastropod. Assassin snails will scale plants, glass, large stones, and wood with surprising speed when hunting for food. I have even seen them suspended upside down on the surface of very still water! Being able to move quickly gives this snail an advantage over slower moving prey items, such as the troublesome pond snail, Physa sp. In large numbers, Physa sp. pond snails can damage soft plant tissue and can present a real problem if you are trying to keep a well-groomed planted aquarium. A handful of Assassin Snails will eventually clear the aquarium of unwanted snails. After the problem snails are eaten, Assassin Snails will take up a somewhat more laid back role by eating left-over fish foods and decaying protein. While some reports of shrimp predation have occurred, it is a pretty rare occurrence.

Watching a group of these curious little snails cruising around your aquarium is really fascinating. I have never really gotten absorbed into the snail world, but seeing the Assassin Snail hunt and forage for food has definitely piqued my interest! From my personal observations, I have to say that these snails are definitely more than capable of ridding an aquarium of unwanted snails. They may be the predator you’ve been looking for.

Thanks, until next time,



  1. avatar

    Will they be offering Assassin snails for sale at That Fish Place?

  2. avatar

    We offer them in the retail store, but they are not available for shipping.

  3. avatar

    I am looking for Assassin snails in the south Denver area. Do you have any stores in that area?

  4. avatar

    Hi Robbie, we only have one retail location in Lancaster, PA. Unfortunately, we do not ship freshwater snails either, but you may be able to find others willing to sell or trade online who may be able to supply you with some.

  5. avatar

    i have Assassin snails in my own aquarium. llike them

  6. avatar

    Hi! At your recommendation we purchased 4 “assassin snails” for our 90 gallon tank to get rid of pond snails that seemed to be taking over the tank. It worked- we no longer have pond snails. But, we were told that these “assassin snails” do not reproduce very quickly- at least not in an aquarium. Well, our original 4 are now well over 100. How do we get rid of these?

  7. avatar

    Adding a skunk loach may be beneficial if you can find one as they prey on snail eggs and baby snails. Freshwater puffers will also dine on snails, but they can be aggressive towards tankmates. If you don’t want to add anything else, try manual removal of those you see, continuing to harvest until the problem is under control. Snailicides are also available, but you’ll need to do an aggressive water change/gravel vac to ensure that the dead snails do not foul your water.

  8. avatar

    I received 4 assissin snails today for my pest snail problem in my 35g planted tank, 1 of them went rite to work on a pond snail, another one came over and tried to take it away, but it was to late, they are great to have and to watch, I recomend then to anyone with a pest snail problem, i hope they have more, i,d prefer them over the pest snails, and they look good too……

  9. avatar

    Thanks for the feedback!! Glad they’re working out for you!!

  10. avatar

    These snails r the best mind blowing… They eat all the unwanted snails in ur aquarium…

  11. avatar

    Hi I have a snail problem. I have a fancy pleco and may have baby fish soon. I was wondering, would an assassin snail attack any of my fish or: my pleco? Thank you

  12. avatar

    Hello Erin, They may feed on them after they die, but Assassin Snails shouldn’t bother live fish.

  13. avatar

    i have a 38 gallon tank. my black molly and red platy gave birth on the same day. lots of baby fish. one day, a month ago, pest snails showed up out the blue. i’ve been researching how to get rid of them. i found out about the assassin snails and the skunk loach. they seem like the answer to my problem. will purchase very soon.

  14. avatar

    Hi Maria, The Skunk Loach may go after any small babies as well but both would help with your snail problem. If you have live plants in the tank, that would most likely be where the snails came from. Good luck!

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