Cod called cod: "Cod" forms part of the common name of many other fish no longer classified in the genus "Gadus". Many are members of the family Gadidae; others are members of three related families within the order Gadiformes whose names include the word "cod": the morid cods, Moridae (100 or so species); the eel cods, Muraenolepididae (four species); and the Eucla cod, Euclichthyidae (one species). The tadpole cod family (Ranicipitidae) has now been placed in Gadidae. Gadiformes include: Some fish have common names derived from "cod", such as codling, codlet or tomcod. ("Codling" is also used as a name for
Dried and salted cod cod was derived exclusively from Atlantic cod. Since then products sold as salt cod may be derived from other whitefish, such as pollock, haddock, blue whiting, ling and tusk. In Norway, there used to be five different grades of salt cod. The best grade was called superior extra. Then came (in descending order) superior, imperial, universal and popular. These appellations are no longer extensively used, although some producers still make the superior products. The best klippfisk, the superior extra, is made only from line-caught cod. The fish is always of the "skrei", the cod that once a year is caught