A medium-sized to large fish (family Salmonidae) with a long, streamlined body, highly prized for food and sport, that inhabits cool waters of the North Atlantic and North Pacific and rivers flowing into them. Most salmon are anadromous, hatching in fresh water where they remain as juveniles, then migrating to the ocean and returning to fresh water to reproduce, usually to the river from which they came. There are two genera. Salmo, with one species (S. salar), is the Atlantic salmon, and the genus Oncorhynchus comprises six species of Pacific salmon: chinook (O. tshawytscha); chum (O. keta); coho (O. kisutch); masu (O. masou); pink (O. gorbuscha); and sockeye (O. nerka). Salmon have been introduced to lakes in several parts of the world, and they are extensively farmed for food.