Rainbow trout are native to the Pacific coast and have been introduced widely to the Big Horns and it's tributaries.  The rainbow, like the cutthroat, is a spring spawner.  Since these two species are fairly closely related, hybridization often occurs.  Because of this rainbows are no longer being stocked in waters containing native populations of cutthroat trout.  Rainbows prefer cool, clear water, either in lakes or streams.  Food of the rainbow in lakes is mainly plankton, but they also eat aquatic insects, small snails, crayfish, and fresh water shrimp.  Larger rainbows prey on smaller fish.  Rainbows are distinguished from the cutthroat by the absence of the basibranchial teeth, no markings under the the jaw, a white tip on the pelvic and anal fins, and more uniform spotting.