Species spotlight- Clea helena- “Assassin snail”
“The freshwater snail Clea helena is a Southeast Asian species closely related to the marine whelks (family Buccinidae). In the trade it is most commonly called the ‘assassin snail’ or ‘snail-eating snail’.
Among scientists it is also known as Anentome helena and as Clea (Anentome) helena. This latter designation reflects the division of the genus Clea into two subgenera, Clea (Clea) and Clea (Anentome) for the Asian species, and Clea (Afrocanidia) for the African species.”
For the longest time I heard many hobbyists say that the long siphon was used in the attack on pest snails, today I caught some pictures of the assassin snail feeding, and was able to photograph the forked mouth appendage used for eating its prey.
These are an easy species to keep, with moderately hard water being best to preserve shell integrity. While they are best known for eating pest snails (ramshorns, malaysian trumpet, pond, and bladder) they will also gang up together to predate upon larger snails like Apple snails. They will also attempt to eat Nerite snails, but are rarely successful. They are very efficient at pest snail control, with each adult snail generally consuming 2-3 pest snails per day. While they are considered shrimp and fish safe, there have been isolated reports of them consuming both, though it is unclear the health of the specific shrimp/snail at the time of attack.
There are also many myths that Assassin snails do not breed. This is quite false. They lay prolifically, with singular eggs being placed in rows among hardscape, the base of stiff plants, as well as inside the poors of filter media. The young are very small and slow growing, and often it is months before the first offspring become visible within the tank.
As a hobbyist, it is important to be aware of the eggs and where they are laid, especially if you move plants from tank to tank, or share them with other hobbyists via internet sales or club auctions. It is very easy to transfer the eggs, and introduce these predators without realizing it. Care should also be taken to make sure that any plants with eggs that are being discarded have been frozen to prevent introduction of the Assassin snail to local waterways.