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a genus of fishes of the family Cyprinidae. There are about ten species, distributed in Europe and in western and northern Asia. The USSR has two species: the vyrezub (R. frissi) and the roach (R. rutilus). The latter is distributed everywhere except the Kolyma River and the Asian portion of the basin of the Pacific Ocean. The body, which is covered with large scales, reaches 25 cm in length and 200 g in weight. There are many freshwater, resident, and semimigratory subspecies. Rutilus feeds on plants, plankton, and benthos. Sexual maturity is attained in the third or fourth year. The females deposit as many as 100,000 eggs in April or May on the previous year’s vegetation. The males have breeding coloration. Rutilus has local commercial significance. The numbers of some commercial subspecies (R. r. aralensis, R. r. heckeli) are noticeably decreasing, and they urgently need protection.