Rainbow Trout Oncorhynchus mykiss

The Rainbow Trout, also called Steelhead in the USA, is mainly a marine fish which enters freshwater rivers to spawn, like salmon. It is native to the northern Pacific Ocean, both North American and Asian coasts, but has also been introduced to the Great Lakes as a freshwater fish and to other countries around the world including the UK. Both freshwater and marine forms are silver with dark spots (some freshwater ones can be goldish); there is a purplish line along each flank which reddens up on spawning males. It typically grows to 50-75cm long but can exceed a metre.