Cod is the common name for the demersal fish genus Gadus, belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus Gadus is commonly not called cod.
Atlantic cod
The Atlantic cod, Gadus morhua
A fish with its gills infested with two cod worms
Preserved codfish
Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes. They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks. In coastal waters, they are found on or near the continental shelf, and in deep waters, they are found on or near the continental slope or along the continental rise. They are not generally found in the deepest waters, such as abyssal depths or on the abyssal plain, but they can be found around seamounts and islands. The word demersal comes from the Latin demergere, which means to sink.
Bluespotted ribbontail ray resting on the seafloor
Rhinogobius flumineus swim on the beds of rivers
Benthic flatfish and benthopelagic cod on a shore – Jan van Kessel senior, 1626–1679
Flounder have both eyes on one side of their head