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,

Craig