Cottus is a genus of the mainly freshwater ray-finned fishes belonging to the family Cottidae, the typical sculpins. They are often referred to as the "freshwater sculpins", as they are the principal genus of sculpins to be found in fresh water. They are native to the Palearctic and Nearctic. They are small fish, mostly less than in length, although a few species can reach twice that size. Taxonomy Cottus was first proposed as a genus by Carl Linnaeus in the 10th edition of the Systema Naturae when he described the European bullhead (Cottus gobio) and in 1850 this species was designated as the type species of the genus by the French ichthyologist Charles Frédéric Girard. The 5th edition of the Fishes of the World classifies this genus within the subfamily Cottinae of the family Cottidae. Other authorities have found that the Cottidae, as delimited in the 5th edition of Fishes of the World, is paraphyletic and that the monophyletic grouping is the freshwater sculpins, including the Baikal sculpins, while most of the marine taxa are classified within the family Psychrolutidae. Cottus kazika has been found to be outside of a monophyletic Cottus and has been classified in the monospecific genus Rheopresbe. Species There are currently around 70 recognised species in this genus: Subgenus Cottus Linnaeus, 1758 Cottus aturi Freyhof, Kottelat & Nolte, 2005 Cottus cyclophthalmus Sideleva, Kesminas & Zhidkov, 2022 Cottus duranii Freyhof, Kottelat & Norte, 2005 (Dordogne sculpin) Cottus dzungaricus Kottelat, 2006 Cottus ferrugineus Heckel & Kner, 1857 Cottus gobio Linnaeus, 1758 (European bullhead) Cottus gratzianowi Sideleva, Naseka & Zhidkov, 2015 Cottus haemusi Marinov & Dikov, 1986 Cottus hispaniolensis Băcescu & Băcescu-Mester, 1964 Cottus jaxartensis Berg, 1916 Cottus koshewnikowi Gratzianov, 1907 Cottus metae Freyhof, Kottelat & Nolte, 2005 Cottus microstomus Heckel, 1837 Cottus perifretum Freyhof, Kottelat & Nolte,, 2005 Cottus petiti Băcescu & Băcescu-Mester, 1964 Cottus rhenanus Freyhof, Kottelat & Nolte, 2005 Cottus ricei E. W. Nelson, 1876 (Spoonhead sculpin) Cottus rondeleti Freyhof, Kottelat & Nolte, 2005 Cottus sabaudicus Sideleva, 2009 Cottus scaturigo Freyhof, Kottelat & Nolte, 2005 Cottus sibiricus Kessler, 1889 (Siberian sculpin) Cottus spinulosus Kessler, 1872 (Turkestan sculpin) Cottus transsilvaniae Freyhof, Kottelat & Nolte, 2005 Subgenus Cephalocottus Gratzianov, 1907 Cottus amblystomopsis P. Y. Schmidt, 1904 (Sakhalin sculpin) Cottus nozawae Snyder, 1911 Subgenus Cottopsis Girard 1850 Cottus aleuticus C. H. Gilbert, 1896 (Coast Range sculpin) Cottus asper J. Richardson, 1836 (Prickly sculpin) Cottus asperrimus Rutter, 1908 (Rough sculpin)