Gadus morhua

Commonly known as the Atlantic cod, is considered a demersal fish, although its habitat may become pelagic under certain hydrographic conditions, when feeding or spawning. The presence of cod usually depends on prey distribution rather than on temperature. However, whatever the reason, larger fish are found in colder waters in most areas(0-5⁰C). It lives in almost any salinity from nearly fresh to full oceanic water, and in a wide range of temperatures from nearly freezing to 20⁰C. While Atlantic fish is essentially a fish of the open sea, it appears regularly in various river mouths in  Maine and Massachusetts during late autumn and winter. 
    The species is widely distributed in a variety of habitats from the shoreline to well down the continental shelf, to depths over 600 m, but is mostly found within continental shelf areas from 150-200 m.
    The size varies, yet the oceanic cod often reaches 1 m and it is known to attain a length of 2 meters.