Rainbow Trout

Oncorhynchus mykiss


Rainbow trout side view photo with black background
Rainbow trout, Oncorhynchus mykiss
Lance Merry

Salmonidae (trouts) in the order Salmoniformes (salmon, trout, chars, and others)


Rainbow trout have small scales and a small, fleshy adipose fin on the back behind the dorsal fin. The fins lack spines. There is a small triangular projection at the base of the pelvic fin. Upper parts are dark olive, thickly speckled with black spots; the belly is silvery white. There are prominent dark spots on the tail. The side lacks orange or reddish spots, but there is a pink or reddish longitudinal stripe. The tail fin is definitely forked; the anal fin usually has 10 or 11 rays.


Total length: 10–15 inches; weight: to 1½ pounds (or more).

Habitat and conservation

Rainbow trout require waters that are constantly below 70°F, so they are limited to Ozark spring branches, spring-fed streams, and Lake Taneycomo, where cold water is discharged from the lower levels of Table Rock Reservoir just upstream. The Missouri Department of Conservation operates trout hatcheries in order to stock them as game fish in our state. Where trout have established self-sustaining populations, creel and size limits help keep those populations healthy.


Rainbow trout eat a variety of animal life, but aquatic insects, terrestrial insects, snails, and small fishes often make up the bulk of its diet.

image of Rainbow Trout distribution map
Distribution in Missouri

Limited to waters that stay below 70°F: Ozark spring branches, spring-fed streams, and Lake Taneycomo.


Although small, self-sustaining populations have been established in some streams, most populations are maintained by continuous stocking.

Life cycle

Wild trout in Ozark springs spawn in late December through early February; hatchery brood stock spawn in October and November. In nature, the female digs a shallow pit on clean, gravelly riffles, fanning it hard with her tail. One or more males fertilize the eggs as they are shed. The female resumes digging upstream, covering the eggs by gravel carried by the current. No parental care is provided. Hatchery-raised trout grow faster than those in the wild, reaching 10 inches their first year.

Human connections

There is a tremendous and growing demand for trout fishing in our state, and trout are raised in hatcheries and released into suitable habitats to meet the demand. Trout angling-related activities contribute millions of dollars to Missouri's economy annually.

Ecosystem connections

Although not native to our state, trout serve a role as a top predator. In areas with complex fish communities where the trout is not the only major predator, trout distribution is more limited.