Chinook are large silver fish and have more spots on their backs than the Coho salmon, a squared-off tail ﬁn, and small black spots on both lobes of the tail ﬁn. The interior of the mouth is black. Mature males develop a hooked upper jaw and enlarged teeth. The anal fin usually has 14 to 19 rays; its base is longer than base of dorsal fin. Adult size: 18 to 40 inches.