The Assassin Snail is an ironic solution to the problem of snails over-running an aquarium, since it has the ability to hunt down and kill other snails. Assassin snails will hunt for any similar sized or smaller snail of another species and literally suck it out of its shell. They are of particular use in controlling the tricky Malayan Trumpet Snail, which can rapidly reproduce and overrun an aquarium. Even the other snails seem to know they are in trouble when assassins are added to the tank, since they can often be seen changing habits and heading up to the surface.
Assassin snails are reportedly not a fast reproducer, so one snail problem will not be swapped for another, and if they do reproduce at least they have value and can be sold on or given away. Once the assassins have cleared up any other snails, which may take some time depending on numbers, they will happily feed on debris and algae wafers although they are not a great algae eater. The assassin snail does not tend to eat its own kind and has a quite attractive shell, so a few can be an ideal addition to a tank in their own right, or as a method to control other snail populations.
No special requirements are needed to keep these snails and they will settle into most tanks without predators.