Salmon is a common name for several species of ray-finned fish in the family Salmonidae. Other fish in the same family include trout, char, grayling, and whitefish. Salmon are native to tributaries of the North Pacific Ocean and the North Atlantic Ocean. Many species of salmon have been introduced into non-native environments such as the Great Lakes of North America and Patagonia in South America. Salmon are intensively farmed in many parts of the world.
The term “salmon” comes from the Latin salmo, which in turn may have originated from salire, meaning “to leap”. The nine commercially important species of salmon occur in two genera: Oncorhynchus and Salmo. Species of Oncorhynchus include coho, pink (also known as humpy), sockeye (also known as red), chinook (also known as king or tyee), masu (also known as cherry), chum (also known as calico or dog), and silver. The type species for genus Oncorhynchus is the pacific salmon Oncorhynchus nerka. Fisheries biologists commonly use these scientific names when referring to these fish with little distinction between them.
Species within Salmo include brown trout, Atlantic salmon, danube salmon, and rainbow trout. Brown trout that live mostly in freshwater streams are commonly called riverine brown trout, while those living mainly downstream from lakes are referred to as lacustrine brown trout.. Trout that live mainly upstream from ponds are referred to as stillwater brown trout;:131 some authorities recognize anadromous forms of this species – so named because they return from ocean feeding grounds to spawn – with different common names including seagoing brown trout or sea Trout.:168 Rainbow trout hatchlings feed on zooplankton before switching to insects,:21 other small crustaceans,:56 small mollusks like snails:229–30 or amphipods,(p169) insect larvae ,and baitfish like sculpin while juvenile and adult rainbow Trout eat larger fish including stream dwelling cutthroat eels up to 20% their length;(p170)(pp380–81) landlocked rainbows raised in hatcheries on dry food pellets typically have less diverse diets including greater proportions of pellets if not entirely made up pelleted foods..