Oncorhynchus mykiss are distinctive by their speckles and red lateral line with an olive dorsal surface and silvery bottom. They turn more silvery while in the ocean. The ones that go to the ocean are called steelhead. The ones that stay in fresh water all their lives are called rainbow trout. Even more acrobatic than the coho, the steelhead return to the streams of their birth to mate. An interesting fact is that rainbow trout spawn in the summer and steelhead come to spawn November to April. The average size for a steelhead is 3-10 kg but they can grow to be up to 25 kg and measure 45 inches long. Steelhead can live up to 11 years.