Chiefly marine; rare in brackish water. All tropical seas, mainly Indo-Pacific. One nostril on each side of head; double nostrils in some species of Chromis and Dascyllus. Body usually deep and compressed. Small mouth. Incomplete and interrupted lateral line. Anal fin with usually 2 spines, very rarely 3. No palatine teeth. About 35 cm maximum length. Coloration variable with individuals and with locality for the same species. Many species are highly territorial herbivores, omnivores, or planktivores. Damselfishes lay elliptical demersal eggs that are guarded by the males. Included are the anemonefishes (Amphiprioninae), which live in close association with large sea anemones. Damsels are among the hardiest aquariumfishes, but some species are extremely aggressive. Poma- = opercle, centron = spine, (refers to pointed margin of opercle); amphi- (gr.) = on both sides, prion = saw, (refers to serrate opercles)