rudd, (Scardinius erythrophthalmus), stout-bodied freshwater sport fish of the carp family, Cyprinidae, similar to the related roach, but more golden, with yellow-orange eyes, deep red fins, and a sharp-edged belly. The rudd is widely distributed in Europe and Asia Minor and has been introduced into the United States, where it is called American, or pearl, roach. It is a schooling fish that frequents thickly planted, reedy lakes and slow rivers and eats plants, small animals, and insects. Maximum length and weight are about 35–40 centimetres (14–16 inches) and 1–2 kilograms (2–4 1/2 pounds).