What is the Colorado state fish? The greenback cutthroat trout holds this honor, designated as the official state fish in 1994. This remarkable native trout represents the Centennial State’s commitment to conservation and its rich fishing heritage. Once thought completely extinct, the greenback cutthroat trout has become a symbol of successful wildlife recovery efforts. Colorado is home to multiple native cutthroat trout subspecies, each with unique characteristics and conservation challenges, making the state’s native trout story one of both triumph and ongoing dedication.
What Is the Colorado State Fish?
The greenback cutthroat trout, scientifically known as Oncorhynchus clarkii somias, is Colorado’s designated state fish. This beautiful native trout displays distinctive features including dark, round spots on the sides and tail, and two colorful blood-red stripes on each side of the throat under the jaw, which gives all cutthroat trout their name. The greenback cutthroat trout originally inhabited the mountain and foothill areas of the South Platte River system in Colorado and part of Wyoming, thriving in cold, clear, gravely headwater streams and mountain lakes.
Colorado chose the greenback cutthroat trout as its state fish because it is the only trout species truly indigenous to the state. Federal officials first listed the greenback cutthroat as extinct in the 1930s due to pollution, competition from nonnative fish species, over-fishing, and habitat loss. Small populations found in 1957, 1965, and 1970 gave hope, but researchers later discovered those populations weren’t purebred greenback trout but rather a similar-looking subspecies. The designation as state fish came after decades of conservation work, recognizing both the species’ unique heritage and the ongoing efforts to restore it to its native range.
Colorado’s Native Cutthroat Trout Subspecies
Colorado harbors four native subspecies of cutthroat trout, each adapted to different watersheds across the state. The Colorado River cutthroat trout inhabits the western slope, with researchers identifying three distinct genetic lineages within its range: one in northwest Colorado, one in the San Juan River basin, and one in the Gunnison and upper Colorado River basins. The Rio Grande cutthroat trout can be found in high elevation streams and lakes of the Rio Grande, Canadian, and Pecos River drainages in Colorado and New Mexico, giving it the southern-most distribution of any form of cutthroat trout. The Snake River cutthroat, though not originally native to Colorado, has been introduced into numerous mountain streams and lakes.
The yellowfin cutthroat trout, once native to Twin Lakes and the Arkansas River Watershed, is thought to be extinct, though Colorado researchers continue to look for unidentified populations. Working with a consortium of state and federal wildlife agencies, Trout Unlimited and other conservation groups, Colorado Parks and Wildlife has developed an aggressive conservation strategy to help restore native cutthroat populations across all subspecies. DNA testing revealed additional genetic lineages beyond what was previously recognized, and comprehensive studies have shown these lineages can also be identified by examining morphological traits such as spotting patterns and physical characteristics.
The Greenback Cutthroat Trout Discovery
In 2012, researchers discovered the world’s only natural, purebred population of greenback cutthroat trout in a 3.5-mile run of Bear Creek near Colorado Springs. Recent studies matching state-of-the-art genetic techniques with physical characteristics found that only this one population shared the genetic fingerprint with specimens collected in the late 1800s. Biologists think homesteaders likely introduced greenbacks to the formerly empty streams in the Bear Creek area more than a century ago, which may have inadvertently saved the species from complete extinction.
Each spring, CPW aquatic biologists strap on heavy electrofishing backpacks to painstakingly hike up Bear Creek to catch greenbacks and collect milt and roe, the sperm and eggs needed for propagation. This electrofishing process involves sending a current through the water to attract and stun the fish, making them easier to catch during spawning season. Colorado Parks and Wildlife is culturing these fish in its hatchery system, with facilities at the Leadville National Fish Hatchery and Mt. Shavano hatchery in Salida playing critical roles in raising greenback cutthroat trout for reintroduction efforts.
Where to Find Cutthroat Trout in Colorado
Anglers can target various cutthroat trout subspecies across Colorado’s diverse waters, though fishing regulations vary by location and subspecies. The greenback cutthroat trout prefers cold, clear, gravely headwater streams and mountain lakes which provide an abundant food supply of insects.
- Turquoise Lake and Twin Lakes: These mountain lakes provide opportunities to catch cutthroat trout in scenic high-elevation settings with good access and facilities for anglers visiting the Centennial State.
- Clear Creek: This Front Range stream flows alongside Interstate 70 through the mountains, offering accessible fishing for cutthroat trout with guidance from local experts who understand the native species that once called these waters home.
- Spinney Mountain Reservoir: Known for quality trout fishing, this South Park reservoir holds cutthroat trout among other species and attracts anglers seeking trophy-sized fish in Colorado’s high country.
- Taylor Reservoir and Elevenmile Reservoir: These productive reservoirs in the South Platte River drainage system offer excellent cutthroat trout fishing opportunities with boat access and shoreline fishing available.
- Lake John and Delaney Buttes: Located in North Park, these waters provide fishing for Snake River cutthroat trout that have been introduced to expand angling opportunities in Colorado’s mountain lakes.
- Trappers Lake: This historic water holds the largest population of native Colorado River cutthroat trout in the world, though the fishery has faced challenges from brook trout competition and whirling disease. Anglers are reminded to decontaminate their gear after fishing at Trappers Lake, particularly before heading into higher elevation lakes such as Little Trappers Lake that remain free of the parasite.
- Zimmerman Lake: The site of the first reintroduction of genetically pure greenback cutthroat trout in August 2014, this water serves as a wild brood stock where biologists continue growing more greenback cutthroat trout for future reintroduction projects.
- Herman Gulch: Near Silver Plume, this stream was populated with newly hatched greenback cutthroat trout beginning in 2016, and by 2022, the fish brought to Herman Gulch became adults and began reproducing without help from humans.
The South Platte River system represents the native range of the greenback cutthroat trout, and state agencies are working on removing nonnative fish from additional streams to provide more places to reestablish the species. State parks across Colorado offer public access to waters holding various cutthroat subspecies.
Best Time to Fish for Cutthroat Trout
Spawning occurs usually from late May to mid-July in higher elevations for greenback cutthroat trout, with timing varying based on water temperatures and snowmelt. Male cutthroat spawn first at age two, and females mature a year later. Rio Grande cutthroat spawn in the spring following runoff, when water temperatures approach 50 degrees Fahrenheit, which takes place from March through July across their range depending on elevation and local conditions.
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, while larger fish of about four to seven pounds will lay up to 6,000 eggs. Understanding spawning behavior helps anglers time their trips and practice responsible fishing during sensitive reproductive periods. Mountain streams and lakes fish best during summer and early fall when access is easiest and fish are actively feeding on aquatic and terrestrial insects.
How to Catch Cutthroat Trout
Cutthroat trout feed primarily on aquatic and terrestrial insects, crustaceans such as fresh-water shrimp, and small fish at larger sizes. This feeding behavior makes them excellent targets for fly fishing and light tackle approaches in Colorado’s clear mountain waters.
- Best Baits: Dry flies, nymphs, and streamers work well for fly anglers targeting cutthroat trout in headwater streams. Small spinners, spoons, and inline lures produce strikes in both streams and lakes. Natural baits like worms and salmon eggs can be effective where regulations permit.
- Gear Setup: Light to medium-weight fly rods in the 3-6 weight range handle most cutthroat trout situations. Spinning anglers should use ultralight to light action rods with 4-8 pound test line to match the delicate presentation needed in clear water.
- Technique Tips: Approach quietly and stay low when fishing clear mountain streams, as cutthroat trout can be easily spooked. Present flies and lures naturally, matching the drift of real insects in the current. Focus on pools, pocket water behind boulders, and undercut banks where trout hold.
Rio Grande cutthroat size is variable and based on the available habitat. In small headwater streams adults are generally 6-10 inches in length, while larger waters can produce bigger specimens. Snake River cutthroat introduced into mountain lakes and streams provide accessible fishing opportunities for anglers of all skill levels.
Conservation Challenges and Efforts
The greenback cutthroat trout is listed as federally threatened and state threatened, reflecting its precarious status despite recent recovery successes. All subspecies of cutthroat trout are the subject of conservation efforts and research by multiple state and federal agencies. A key component of cutthroat conservation involves egg-collection, hatchery and stocking programs that help establish new populations in suitable habitats.
The Colorado River cutthroat trout is designated as a species of special concern in Colorado, and significant resources have been dedicated to conservation of the subspecies. The Rio Grande cutthroat trout currently occupies just 12 percent of its historic habitat in approximately 800 miles of streams, with biologists estimating that 127 conservation populations now exist in Colorado and New Mexico, of which 57 are considered secure. The historic range of Rio Grande cutthroat trout has been reduced over the last 150 years due to drought, water infrastructure, habitat changes, hybridization with nonnative rainbow trout and other cutthroat subspecies, and competition with brook trout and brown trout.
Where habitats home to pure cutthroat trout have been invaded by nonnative salmonids, it is important to replicate those populations before they disappear entirely. Progeny from hatchery operations are used for founding new populations in waters that have been cleared of nonnative fish that otherwise replace cutthroat trout or hybridize with them. Trappers Lake historically was home to Colorado’s premier wild Colorado River cutthroat trout fishery, but reduced cutthroat trout numbers have been attributed to a burgeoning brook trout population now being thinned by fall trapping efforts. Whirling disease invaded the Trappers Lake population in the late 1990s and has firmly established itself, suppressing recruitment of cutthroat trout further.
In 2020, CPW reported an 80 percent decline in adult trout populations over a three year period due to a combination of disease, rising temperatures, and other factors. The greenback trout also faces competition from nonnative predators like brook trout and brown trout, who have invaded local ecosystems. The first conservation agreement for Rio Grande cutthroat trout between state, federal, and tribal resource agencies was signed in 2003, giving rise to the Rio Grande Cutthroat Trout Conservation Team with the stated goal to assure the long-term viability of the subspecies throughout its historic range.
Frequently Asked Questions
What is a greenback cutthroat?
A greenback cutthroat is Colorado’s state fish, scientifically known as Oncorhynchus clarkii somias. This native trout displays distinctive red slashes under its jaw and dark spots on its sides and tail. Once thought extinct, the only remaining pure population was discovered in Bear Creek near Colorado Springs in 2012, making it one of the rarest trout subspecies in North America.
What fish is native to Colorado?
Cutthroat trout are the only trout species truly native to Colorado. The state harbors four native subspecies: the greenback cutthroat in the South Platte River basin, the Colorado River cutthroat on the western slope, the Rio Grande cutthroat in southern Colorado, and the now-extinct yellowfin cutthroat. All other trout species found in Colorado waters, including rainbow trout, brook trout, and brown trout, were introduced by humans.
How rare are greenback cutthroat trout?
Greenback cutthroat trout are extremely rare, with only one natural purebred population discovered in a 3.5-mile stretch of Bear Creek. The species was declared extinct in the 1930s and remains federally listed as threatened. Thanks to intensive conservation work by Colorado Parks and Wildlife and partner agencies, hatchery-raised greenbacks are now being reintroduced to waters like Zimmerman Lake and Herman Gulch, where they have successfully begun reproducing on their own.
Experience Colorado’s Native Trout Heritage
The state fish of Colorado represents more than just an angling opportunity—it embodies the Centennial State’s dedication to preserving its natural heritage. Whether you’re casting flies in high mountain streams for Rio Grande cutthroat or exploring the recovery of greenback cutthroat trout in their native South Platte drainage, Colorado offers unique chances to connect with truly wild native trout. Visit Colorado’s pristine waters and become part of the conservation story that saved these remarkable fish from extinction.