gadiform

— Codfish include ten families with more than 200 species. Almost all live in cold salt water in the Northern Hemisphere. Cod were thought to have developed into their current forms about 120 million years ago in the Tethys Sea, a tropical sea that once ran around the earth east-west and connected all other oceans. Eventually the Tethys merged with a northern sea, and the cod became a fish of the North Atlantic. Later, when a land bridge between Asia and North America broke, cod found their way into the northern Pacific. In gadiform fish, evolution is seen in the fins. The cusk has almost a continuous single fin around the body with a barely distinct tail. The ling has a distinct tail and a small second dorsal fin. On a hake, the forward dorsal fin becomes even more distinct. On a whiting, there are three dorsal fins, and the anal (belly) side has developed two distinct fins. On the most developed gadiforms—cod, haddock, and pollock—these three dorsal and two anal fins are large and very separate. […] There are other gadiforms that are pleasant to eat but of no commercial value. […] But to the commercial fisherman, there have always been five kinds of gadiform: the Atlantic cod, the haddock, the pollock, the whiting, and the hake. Increasingly, a sixth gadiform must be added to the list, the Pacific cod, Gadus macrocephalus, a smaller version of the Atlantic cod whose flesh is judged of only slightly lesser quality.

— Near-synonyms: gadoid, codlike