Colorado State Fish

Greenback Cutthroat Trout

Colorado State Fish - Greenback Cutthroat Trout

(Oncorhynchus clarki somias)

Adopted on March 15, 1994.

The Greenback Cutthroat Trout, (Oncorhynchus clarki somias,) was adopted as the official state fish on March 15, 1994, by an act of the General Assembly. The Rainbow Trout was considered the state fish from 1954 until 1994, however it was never officially adopted. The Greenback Cutthroat Trout was at one time indigenous to many small creeks, streams and rivers throughout most of Colorado.

As mining and human occupation expanded across the state, the greenback easily succumbed to pollution from mine tailings in the state's streams and to competition from other species of trout introduced to Colorado waters. The demise was so complete that up until the late 1980's biologists feared the extinction of this native fish. However, researchers in the early 1990's discovered several small populations of the greenback in a few remote streams in Rocky Mountain National Park. Colorado Division of Wildlife and National Park personnel took immediate steps to protect and propagate the greenback. Plans have been made to reintroduce this colorful fish to other waters within the state which are suitable for its repopulation.

Citation: House Bill 1164, 1994; Colorado Revised Statute 24-80-911.5.

Colorado State Fish:Greenback Cutthroat Trout

Colorado State Fish - Greenback Cutthroat Trout

The greenback cutthroat trout (Oncorhynchus clarkii stomias) is the easternmost subspecies of cutthroat trout. The greenback cutthroat, once widespread in the Arkansas and South Platte River drainages of Eastern Colorado and Southeast Wyoming, today occupies less than 1% of its historical range. It is currently listed as threatened under the Endangered Species Act. It was adopted as the state fish of Colorado on March 15, 1994 replacing the unofficial rainbow trout.

Characteristics of the Greenback Cutthroat Trout

Greenback cutthroat trout are cold-water fish belonging to the trout, salmon and whitefish family. They have dark, round spots on the sides and tail and two colorful blood-red stripes on each side of the throat under the jaw, hence the name "cutthroat." During the spring spawning season the entire belly may become crimson red.

The greenback cutthroat's maximum size is 18 inches (46 cm). It has the largest spots of all cutthroats and is reported to have the most brilliant spawning coloration. Like all cutthroats, it has red coloration in the area of the lower jaw and throat. Historically, it has been reported to grow as large as 4.5 kilograms (9.9 lb.)


The greenback cutthroat trout was once indigenous to many small creeks, streams and rivers throughout most of Colorado. But it disappeared from many streams after Colorado was settled. The main culprits were mine tailings and competition from other trout species.

Spawning occurs usually from late May to mid-July in higher elevations. Male cutthroat spawn first at age two, and females mature a year later. Females build an egg pit in gravel generally three to eight inches deep and one foot in diameter. A 10-inch female will lay about 800 eggs. Larger fish of about four to seven pounds will lay up to 6,000 eggs.

Up until the late 1980's biologists feared the greenback might be extinct. But in the early 1990's, researchers found several small populations in Rocky Mountain National Park.

With protection, the greenback is now recovering its numbers. There are plans to reintroduce the colorful fish to other streams where it once swam

Colorado Law

The law designating the greenback cutthroat trout as the official Colorado state fish is Section 24-80-911.5 (State fish) of the Colorado Revised Statutes, specifically Title 24 (GOVERNMENT - STATE - STATE HISTORY, ARCHIVES, AND EMBLEMS) Article 80 (STATE HISTORY, ARCHIVES, AND EMBLEMS) Part 9 (STATE EMBLEMS AND SYMBOLS), Section 24-80-911.5.


24-80-911.5. State fish.

The greenback cutthroat trout (Oncorhynchus clarki stomias) is hereby made and declared to be the state fish of the state of Colorado.

Source: L. 94: Entire section added, p. 50, ? 1, effective March 15.

Taxonomic Hierarchy: Greenback Cutthroat Trout

Kingdom: Animalia - animals
Phylum: Chordata
Class: Osteichthyes
Order: Salmoniformes
Family: Salmonidae
Genus: Oncorhynchus
Species: Oncorhynchus clarki somias

State Fishes
State Fish