Rainbow trout are native to the Pacific coast and have been introduced widely to Wyoming.
Rainbow are presently the most important fish used in Wyoming's hatchery system. The rainbow, like the cutthroat, is a spring spawner. Since these two species are fairly close relatives, hybridization often occurs. Because of this, rainbow are no longer being stocked in waters containing native populations of cutthroat trout. Rainbow prefer cool, clear water, either streams or lakes, with maximum water temperatures below seventy degrees Fahrenheit.