The northern whitefin gudgeon (Romanogobio belingi) is a species of freshwater fish in the family Cyprinidae. It is distributed in the northern Black Sea basin (Dniester, Southern Bug, and Dnieper riverine systems), southern Baltic Sea basin (Oder, Vistula), southern North Sea basin (Elbe, Rhine). Also, reports from lakes Ilmen and Ladoga and its basins have been made, which are questionable. Their maximal length is 11.5 cm, with a maximal reported age of 5 years. Diagnosed from its congeners in Baltic and Black Sea basins by the following characters: longitudinal epithelial crests on predorsal scales; scales on lateral line 39-42 + 2; scale rows around caudal peduncle 14-16, rarely 12; dorsal fin with 7½ branched rays; anal fin with 6½ branched rays; dorsal behind middle of body, predorsal length greater than postdorsal length; anus closer to pelvic origin than to anal origin; snout longer than or equal to postorbital distance.
