The eelpouts are the ray-finned fish family Zoarcidae. As the common name suggests, they are somewhat eel-like in appearance. All of the roughly 300 species are marine and mostly bottom-dwelling, some at great depths. Eelpouts are predominantly found in the Northern Hemisphere. The arctic, north pacific and north Atlantic oceans have the highest concentration of species, however species are found around the globe.
They are conventionally placed in the "perciform" assemblage; in fact, the Zoarcoidei seem to be specialized members of the Gasterosteiformes-Scorpaeniformes group of Acanthopterygii.
The largest member of the family is Zoarces americanus, which may reach 1.1 m in length. Other notable genera include Lycodapus and Gymnelus.
Taxonomy
The eelpout family was first proposed as the family Zoarchidae in 1839 by the English naturalist William John Swainson but the spelling was changed to Zoarcidae after the spelling of the genus Zoarces was corrected by Theodore Gill in 1861. The 5th edition of Fishes of the World classifies this family within the suborder Zoarcoidei, within the order Scorpaeniformes. Other authorities classify this family in the infraorder Zoarcales wihin the suborder Cottoidei of the Perciformes because removing the Scorpaeniformes from the Perciformes renders that taxon non monophyletic.
Fishes of the World mentions four subfamilies but does not assign genera to the subfamilies but these were set out in Anderson and Federov's Annotated Checklist and this has been followed by FishBase and Catalog of Fishes.
Subfamilies and genera
The eelpouts are classified into four subfamilies and 61 genera with around 300 species:
subfamily Gymnelinae Gill, 1863
Andriashevia Fedorov & Neelov, 1978
Barbapellis Iglésias, Dettai & Ozouf-Costaz, 2012
Bilabria Schmidt, 1936
Davidijordania Popov, 1931
Ericandersonia Shinohara & Sakurai, 2006
Gymnelopsis Soldatov, 1922
Gymnelus Reinhardt 1834
Hadropareia Schmidt, 1904
Krusensterniella Schmidt, 1904
Magadanichthys Shinohara, Nazarkin & Chereshnev, 2006
Melanostigma Günther, 1881
Nalbantichthys Schultz, 1967
Opaeophacus Bond & Stein, 1984
Puzanovia Fedorov, 1975
Seleniolycus Anderson, 1988
subfamily Lycodinae Gill, 1861
Aiakas Gosztonyi, 1977
Argentinolycus Matallanas & Corbella, 2012
Austrolycus Regan, 1913
Bellingshausenia Matallanas, 2009
Bentartia Matallanas, 2010
Bothrocara Bean, 1890
Bothrocarina Suvorov, 1935
Crossostomus Lahille, 1908
Dadyanos Whitley, 1951
Derepodichthys Gilbert, 1896
Dieidolycus Anderson, 1988
Eucryphycus Anderson, 1988
Exechodontes DeWitt, 1977
Gosztonyia Matallanas, 2009
Hadropogonichthys Fedorov, 1982
Iluocoetes Jenyns, 1842
Japonolycodes Shinohara, Sakurai & Machida, 2002
Letholycus Anderson, 1988
Lycenchelys Gill, 1884
Lycodapus Gilbert, 1890
Lycodes Reinhardt, 1831
Lycodichthys Pappenheim, 1911
Lycodonus Goode & Bean, 1883
Lycogrammoides Soldatov & Lindberg, 1928
Lyconema Gilbert, 1896
Maynea Cunningham, 1871
Notolycodes Gosztonyi, 1977
Oidiphorus McAllister & Rees 1964
Ophthalmolycus Regan, 1913
Pachycara Zugmayer. 1911
Patagolycus Matallanas & Corbella, 2012
Petroschmidtia Taranetz & Andriashev, 1934
Phucocoetes Jenyns, 1842
Piedrabuenia Gosztonyi, 1977
Plesienchelys Anderson, 1988
Pogonolycus Norman, 1937
Pyrolycus Machida & Hashimoto, 2002
Santelmoa Matallanas, 2010
Taranetzella Andriashev, 1952
Thermarces Rosenblatt & Cohen, 1986
Zestichthys Jordan & Hubbs, 1925
subfamily Lycozarcinae Andriashev, 1939
Lycozoarces Popov, 1935
subfamily Zoarcinae Swainson, 1839
Zoarces Cuvier 1829
Characteristics
The body of eelpouts is relatively elongated and laterally compressed. Their heads are relatively small and ovoid. Juveniles have a more rounded snout and relatively larger eye than adults. Their scales are absent or very small. The dorsal and anal fins are continuous down their bodies up to their caudal fin. They produce the pigment biliverdin, which turns their bones green. This feature has no apparent evolutionary function and is harmless. Overall, there is no sexual dimorphism.