common sport and food fish of the carp family, Cyprinidae, widely distributed in rivers and lakes of Europe and western Siberia. An elongated, rather stout fish, the ide is blue-gray or blackish with silvery sides and belly, and is usually about 30–50 cm (12–20 inches) long. It eats fish and insects and other invertebrates. The golden ide is a hardy, reddish gold variety of the species commonly kept in pools and park lakes.