CICHLID. The fishes of the family Cichlidae are perches with a single nostril on each side and with the lower pharyngeals coalesced or united by suture. They are found in lakes, rivers and brackish lagoons of Central and South America, Africa and Syria, Madagascar and India. This distribution was formerly considered to favour the idea of the persistence of the connection between South America and Africa into the Eocene, but the value of the Cichlids in this relation is discounted by the fact that many species enter brackish water and some the sea. Their pres ence in Madagascar, where none of the true freshwater African families is represented, indicates that their dispersal has been accomplished in a manner different from these.
The American species number about 250, the African 40o; none of the genera is common to the two continents. The Indian Etroplus is an isolated genus, related only to Paretroplus of Mada gascar, in which island the genera are peculiar, the two others being related to African genera. In the African Cichlid fauna an extraordinary diversity and specialization is attained in the great lakes, Tanganyika having 10o species, nearly all belonging to genera found only in the lake, and Nyassa having nearly as many endemic species, some of which have evolved on parallel lines to those of Tanganyika. The lacustrine genera differ from each other, especially in modifications of the mouth and teeth, enabling these fishes to make use of every kind of animal and vegetable food available in the lakes. Many Cichlids are beautifully coloured, and are favourite aquarium fishes. Herichthys cyanoguttatus of Mexico, covered with bright blue spots, is one of the really handsome species. Pterophyllum scalare of the Amazon has the body very deep and strongly compressed and the dorsal and anal fins high. Tilapia nilotica, the bolti of the Nile, reaches a length of 18 inches.
In many Cichlids the female fish keeps the eggs in her mouth until they hatch, and for a time swims with her brood, opening her mouth for the little fishes to swim in when danger threatens. In other species the eggs are laid in a hollow scooped out by the male; both parents guard the nest until the eggs hatch, when the mother takes the young into her mouth. (C. T. R.)