Comephorus

the only genus offish of the Comephoridae family of the Percomorphi order. The body is bare and of a delicate rose color. There are no abdominal fins, and the pectoral fins are very long. There are two species, both living only in Lake Baikal. The Baikal oil-fish (C. baicalensis) may be as much as 19 cm long and is very fatty; it generally keeps to the middle depths of the lake and is never found deeper than 800 m. The lesser Baikal oil-fish (C. dybowskii) reaches 15 cm in length and stays mainly in depths of 250–500 m; at night it is found at 50–100 m and near the surface; sometimes it goes as deep as 1 km. Both species of Comephorus are viviparous. They are characterized by an extremely small number of males. (Among the Baikal oil-fish only 3 percent are males; among the lesser Baikal oil-fish, 12–20 percent are males.) In both species the females are larger than the males. The fish have no commercial importance.