tilapia (təläˈpēə) [key] or St. Peter's fish, a spiny-finned freshwater fish of the family Cichlidae, native chiefly to Africa and the Middle East. Fish of the genera Oreochromis, Sarotherodon, and Tilapia, all commonly known as tilapias, have laterally compressed bodies like those of sunfish, are fast growing, and tolerate brackish water. True tilapias are nest brooders, but species of the other genera incubate their eggs orally; one or both parents carry them in their mouths until (and for a short period after) the young hatch. They are economically important as food fishes, both in their native regions and elsewhere, where they have been introduced or are grown on fish farms. The Nile tilapia ( Oreochromis niloticus ) may have been farmed in ancient Egypt, and the most commercially important tilapia of aquaculture are Oreochromis species and their hybrids. Tilapias have a mild-tasting flesh, but the skin has a bitter flavor. Tilapias are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Perciformes, family Cichlidae.