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a genus of fishes of the family Cyprinidae. There are 18 species, distributed in the freshwaters of Europe and Southwest Asia. The USSR has five species, the most common being C. nasus. The body length reaches 50 cm, and the weight 1.5 kg. C. nasus is distributed in Central European rivers that empty into the North and Baltic seas; it is also encountered in the basins of the Black and Caspian seas. It is typically a benthic shoal fish. The fish is found mainly in rivers; it is rarely encountered in lakes. It feeds on fouling vegetable organisms, which it scrapes off stones with its lower lip. Sexual maturity is attained in the third or fourth year. In April or May, in a rapid current, the fish deposits 12,000 sticky roe among stones. The males have brilliant breeding colors. Chondrostoma are of minor commercial value. Their numbers in rivers with regulated currents are sharply decreasing.