Trout represents the oldest aquaculture industry in North America, dating back to the first trout hatchery in the 1880s. Today, Idaho accounts for 70 percent of the rainbow trout raised in the United States. All rainbow trout sold domestically are farmed, either in concrete raceways or earthen ponds. In 1989, the Latin name Oncorhynchus mykiss replaced its predecessor, Salmo gairdneri. So, when looking up information in older technical and cooking publications, S. gairdneri is the name to look for. However, the rainbow trout is still a member of the salmon family. It is silver with black spots on the sides, back and fins. The term rainbow can be misleading, since the skin is not rainbow hued but pinkish lavender. Steelhead trout is a seagoing strain of rainbows. Rainbows usually refer to freshwater fish. Farm-raised rainbows reach market size of 8 to 10 ounces in eight to 12 months.