Codfishes (gadoids) could be described as the archetypical fishes of Icelandic waters and the ecosystem around Iceland could also be described as a codfish dominated ecosystem; such is their importance. Almost all of them are demersal fishes, that is they are usually found near the bottom. The main exception is the blue whiting (Micromesistius poutassou) which is a pelagic fish, living close to the surface.

Most important, of course, is the cod (Gadus morhua) itself which has nearly always been Iceland’s no. 1 export and source of income. Of less importance, but usually included among the 5 most commercially important species, are the haddock (Melanogrammus aeglefinus) and the saithe (or coalfish - Pollachius virens).

Below these in importance are the blue whiting, ling (Molva molva) and the tusk (or cusk - Brosme brosme), species that have long been of commercial interest, but have not been placed in the ranks of the most important species. Still further down the list come the blue ling (Molva dypterygia) and whiting (Merlangius merlangus), species that have sustained regular catches, but usually as bycatch in other fisheries.

This is by no means a complete list of codfish types in Icelandic waters, as a total of 37 species have been recorded there. Some, like the grenadiers (or rattails - macrouridae) are common in deep waters south of Iceland but not in the colder northern deep.

Many small codfish species are also found. Of these, only one, the Norway pout, (Trisopterus esmarkii) has sustained some catches. It is very common to the south and west of Iceland, but sometimes also found in the north. Other smaller gadoids that are actually more common in the colder waters of the north are the Arctic cod (Boreogadus saida), Arctic rockling (Gaidropsarus argentatus) and four-beard rockling (Enchelyopus cimbrius).