Bitterling

Bitterling (Rhodeus sericeus amarus) — small freshwater fish, the carp family (Cyprinidae), with high, laterally compressed body, with large scales and an elongated the dorsal fin. Color of the silver fish, males with a narrow dark stripe, most pronounced on the caudal peduncle.
It lives in slow-flowing and standing waters, usually in areas with sandy and rocky bottom. Avoid muddy waters. It forms small flocks, constantly adhering to the bottom. In Belarus, there is everywhere, but quite rare, usually in rivers Polessye.