Which freshwater fish is commonly called the rudd, a European species with red fins?

The fish commonly called the rudd is Scardinius erythropthalmus.

The common rudd is a freshwater cyprinid native to much of Europe and parts of western Asia. It is usually found in still or slow-moving waters with abundant vegetation, including lakes, ponds, canals and gently flowing rivers.

Its golden or bronze body, upturned mouth and reddish fins are characteristic. The species feeds near the surface and can take insects, plant material and small aquatic animals. It is also kept in some ornamental ponds and has been introduced beyond its native range.

Rudd are often confused with the roach, Rutilus rutilus, because both are common European cyprinids. Rudd usually have a more strongly upturned mouth and a dorsal fin set farther back on the body. The two species can also hybridize.