Me too, had to look it up
coho

or silver salmonSpecies (Oncorhynchus kisutch) of salmon prized for food and sport that ranges from the Bering Sea to Japan and the Salinas River of Monterey Bay, Cal. It weighs about 10 lbs (4.5 kg) and is recognized by the small spots on the back and upper tail-fin lobe. Young cohos stay in freshwater for about one year before entering North Pacific waters; they mature in about three years. Some landlocked populations spend their entire lives in freshwater. Cohos were successfully transplanted in the 1970s into Lake Michigan as a game fish.