Cottus rhenanus is a species of freshwater ray-finned fish belonging to the family Cottidae, the typical sculpins. It is found in France, Belgium, Germany, Luxembourg, and the Netherlands. It inhabits the Rhine and Meuse river drainages. In Rhine extending upriver (southwards) to about Mannheim, including tributaries of River Main and Neckar in Germany. It reaches a maximum length of 10 cm. It prefers streams with clear, cool, moderate to swift water and stone substrate. Here, it mostly occurs in the shallow parts of streams. This species was described as a separate species from the European bullhead (C. gobio) in 2005 by Jörg Freyhof, Maurice Kottelat and Arne W. Nolte. The specific name rhenatus means belonging to Rhenus, the Latin name of the River Rhine. Anal soft rays: 11 - 14. Differs from other species of Cottus in North Sea basin by the combination of the following characters, none of them unique: no distinct transverse bands on pelvic fin; prickling on body absent or only under pectoral fin; base of first dorsal fin with faint black blotches at anterior and posterior extremities; depth of caudal peduncle 26-31% HL; lateral line complete; and unique molecular markers.
