Illinois Exotic Species:
rainbow trout Oncorhynchus mykiss

The average life span of a rainbow trout is six years. Its average weight is one pound in streams and five pounds in Lake Michigan, and it has an average length of 10 to 15 inches. The back of this fish is olive green, the sides are silvery with a pink stripe and the belly is silvery. Spots are present on the back, dorsal fin and caudal fin. The tail is forked. The adipose fin has a black edge.

It reaches maturity at age three. Spawning occurs in spring. The female deposits 500 to 9,000 eggs which are buried in gravel. Eggs hatch in 30 to 100 days. The rainbow trout eats insects, snails and small fishes. Native to the Pacific coast of North America, the rainbow trout lives in Lake Michigan and is stocked in many lakes and streams throughout Illinois.

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