Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Class Osteichthyes Huxley, 1880 [paraphyletic] - bony fishes see [unranked] Euteleostomi
         Subclass Actinopterygii Woodward, 1891 - ray-finned fishes see Class Actinopterygii Woodward, 1891
           Infraclass Neopterygii Regan, 1923 see Subclass Neopterygii Regan, 1923
             Division Teleostei Müller, 1845 see Infraclass Teleostei Müller, 1845
               Subdivision Elopomorpha Greenwood et al., 1966 see Cohort Elopomorpha Greenwood et al., 1966
                 Order Anguilliformes Rafinesque, 1810 - eels
                   01 Family Anguillavidae Hay, 1903, incertae sedis
                   02 Family †Paranguillidae
                   03 Family Moringuidae Gill, 1885 - spaghetti eels
                   04 Family Myrocongridae Gill, 1890
                   05 Family Xenocongridae Regan, 1912 - false moray eels see Family Chlopsidae Rafinesque, 1815
                   06 Family Muraenidae Rafinesque, 1815 - morays
                   07 Family Heterenchelyidae Regan, 1912
                   08 Family Dyssomminidae Böhlke & Hubbs, 1951
                   09 Family †Proteomyridae
                   10 Family †Anguilloididae
                   11 Family †Milananguillidae
                   12 Family Muraenesocidae Kaup, 1859 - pike conger eels
                   13 Family Neenchelyidae Bamber, 1915 see Family Ophichthidae Günther, 1870
                   14 Family Nettastomatidae Kaup, 1859 - duckbill eels
                   15 Family Nessorhamphidae see Family Derichthyidae
                   16 Family Congridae Kaup, 1856 - conger eels
                   17 Family Ophichthidae Günther, 1870 - snake eels and worm eels
                   18 Family Todaridae Greenwood, Rosen, Weitzman & Myers, 1966
                   19 Family Synaphobranchidae Johnson, 1862 - cutthroat eels
                   20 Family Simenchelyidae Gill, 1879 see Subfamily Simenchelyinae
                   21 Family Dysommidae Gill, 1893 see Family Synaphobranchidae Johnson, 1862
                   22 Family Derichthyidae - longneck eels
                   23 Family Macrocephenchelyidae Fowler, 1934 see Family Congridae Kaup, 1856
                   24 Family Serrivomeridae Trewavas, 1932 - sawtooth eels
                   25 Family †Patavichtidae Carroll, 1988, nom. null. see Family Patavichthyidae
                   26 Family Nemichthyidae Kaup, 1859 - snipe eels
                   27 Family Cyemidae Regan, 1912 see Family Cyematidae Regan, 1912
                   28 Family Aoteidae Phillipps, 1926 see Family Ophichthidae Günther, 1870
                   29 Family †Urenchelyidae Woodward, 1900
                   30 Suborder Saccopharyngidae Carroll, 1988, nom. null. see Suborder Saccopharyngoidei