In salt water coho are bluish with sliver sides, small distinct round spots on the back and upper lobe of the tail. Female are paler. Coho are smaller and slimmer then chinook. Inside of the mouth is gray or black with teeth set in white gums.
Teeth are needlelike and firmly set.
The spawning colors of coho salmon are reddish sides with dark black. Length to 38 inches, with wight to 31 pounds. Coho prefer open water, nearer the surface. Coho enter streams from September to October and spawn from October to December. They prefer gravel in small, unspoiled streams.