Distinguished from other European freshwater species by the following characters: 2 dorsals with the first with 6-8 simple rays, and the second with 2-3 simple and 8-12 branched rays; no spines on first dorsal; no barbels; pelvics not fused into a disc; no lateral line canals; males during spawning period, develop a hump on nape and become black with bright green spots on body and unpaired fins (Ref. 59043).