Illustration by Steven Schalla, FlyFishingtheSierra.com, used with permission
A native of the north Pacific coast, Rainbow Trout were stocked in the United States as far back as the 19th century, and are now the most widely distributed wild trout species in the world, from Europe to New Zealand. Even in states within its native range, survivors of stocked coastal rainbows are displacing native redband trout in remote, interior streams.
Rainbows have a sleek, streamlined shape, adipose fin, and soft-rayed dorsal fin. The rainbow can be distinguished from other salmonids by the presence of small dark spots dorsally, and on the entire caudal (tail) fin. The upper half of the body is often a dark olive or steel blue color but this can be highly variable. The rainbow often has a pinkish-red lateral stripe on the sides and similarly colored gill covers, though this can sometimes can appear nearly silver when the trout are not spawning. Males are generally more colorful than females and, during spawning, often develop an elongated jaw and snout that curve in at the ends toward the mouth. Sea-run rainbows are known as “steelhead” and are described separately.