Gadiformes

Common characteristics include the positioning of the pelvic fins (if present), below or in front of the pectoral fins. Gadiformes are physoclists, which means their swim bladders do not have a pneumatic duct. The fins are spineless. Gadiform fish range in size from the codlets, which may be as small as 7 cm (2.8 in) in adult length, to the Atlantic cod, Gadus morhua, which reaches up to 2 m (6.6 ft).

The earliest gadiforms are Palaeogadus weltoni from the Maastrichtian of the United States and the undescribed, informally named "Protocodus" from the Early Paleocene of Greenland.

Taxonomy

The following classification is based on Eschmeyer's Catalog of Fishes:

• Order Gadiformes
  • Suborder Stylephoroidei
    • Family Stylephoridae Swainson, 1839 (tube-eyes or threadtails)
  • Suborder Bregmacerotoidei
    • Family Bregmacerotidae Gill, 1872 (codlets)
  • Suborder Gadoidei
    • Genus †Rhinocephalus Casier, 1966 (fossil; Early Eocene of England)
    • Family Phycidae Swainson, 1838 (phycid hakes)
    • Family Gaidropsaridae Jordan & Evermann, 1898 (rocklings)
    • Family Lotidae Bonaparte, 1835 (hakes and burbots)
    • Family Gadidae Rafinesque, 1810 (cods and haddocks)
  • Suborder Ranicipitoidei
    • Family Ranicipitidae Bonaparte, 1835 (tadpole fishes)
  • Suborder Merluccioidei
    • Family Merlucciidae Rafinesque, 1815 (merlucciid hakes)
  • Suborder Macrouroidei
    • Family Euclichthyidae Cohen, 1984 (Eucla cods)
    • Family Muraenolepididae Regan, 1903 (eel cods)
    • Family Melanonidae Goode & Bean, 1896 (arrowtails or pelagic cods)
    • Family Trachyrincidae Goode & Bean, 1896 (armoured grenadiers)
    • Family Moridae Moreau, 1881 (codlings or deepsea cods)
    • Family Macruronidae Regan, 1903 (blue grenadiers)
    • Family Lyconidae Günther, 1887 (Atlantic hakes)
    • Family Bathygadidae Jordan & Evermann, 1898 (rattails)
    • Family Steindachneriidae Parr, 1942 (luminous hakes)
    • Family Macrouridae Bonaparte, 1831 (grenadiers or rattails)