Assassin Snails (Clea helena) are one of the most useful animals in the aquarium hobby. They will obliterate unwanted pest snails and eliminate the need to use harsh, snail-killing chemicals in your aquarium. They are particularly adept at handling populations of pond snails, Malaysian trumpet snails, ramshorn snails, bladder snails, and more!
To demonstrate an example of the Assassin Snail’s prowess, we have kept several 30 gallon tanks that were completely overrun with hundreds of unwanted pest snails, and a crew of 5 “assassins” demolished them within a couple of weeks. They eat all other types of snails that are their size or smaller, but they will not harm snails that are larger (such as Mystery Snails, Giant Sulawesi Snails, and larger Nerite Snails). However, large groups of Assassin Snails have been known to gang up on a larger snail and take it down, so caution should be exercised when keeping these, even with larger snails. They are safe to keep with fish, most invertebrates, live plants, and other aquarium inhabitants because their preferred meal are snails. But some caution needs to be taken when housing them with dwarf shrimp. There is a slight risk of an assassin snail eating a dwarf shrimp from time to time. They would much prefer to eat snails, but if given the opportunity there is a chance they could get a shrimp. So caution must be used when housing with other snails and dwarf shrimp.