The
rainbow trout (
Oncorhynchus mykiss) is a
trout and species of
salmonid native to cold-water
tributaries of the Pacific Ocean in Asia and North America. The
steelhead (sometimes called "steelhead trout") is an
anadromous (sea-run) form of the
coastal rainbow trout or
Columbia River redband trout that usually returns to fresh water to
spawn after living two to three years in the ocean. Freshwater forms that have been
introduced into the
Great Lakes and migrate into tributaries to spawn are also called steelhead.