Lithopoma tectum

Acclimation: very slow. LiveAquaria recommends drip acclimation over several hours, because it does not tolerate even small changes in water parameters.

Setup: an established tank with plenty of algae-covered rock to graze, hiding places and room to roam. It also cleans the glass, but climbs less than small snails do.

The key point: it has difficulty righting itself when it falls or is knocked over (LiveAquaria; Quality Marine says so of the genus Lithopoma). Check on it daily and turn it upright if you find it on its back on the sand, otherwise it may die or be eaten.

Tankmates: peaceful and harmless to corals and other invertebrates ("reef safe" for LiveAquaria and Quality Marine).

Sensitivities: high nitrate and copper-based medications. LiveAquaria recommends calcium and trace elements to maintain the shell.

A strict herbivore, it prefers hair algae, cyanobacteria and diatoms. Aquarists report that it eats the whole hair-algae tuft, which slows regrowth (LiveAquaria).

If algae run short, supplement with blanched spinach or lettuce, vegetable tablets (LiveAquaria) or dried seaweed (Quality Marine). A grazing snail with nothing left to eat wastes away: match the number of snails to the amount of algae in the tank.