Threatened and Endangered Fish in Colorado

Dams, diversions and introduced predators drive most of these listings. The Upper Colorado River Endangered Fish Recovery Program says smallmouth bass, northern pike and walleye are "the biggest obstacle to the recovery of rare native fish in the rivers"; they eat native fish and compete with them (nonnative fish). Low, regulated flows are the other half of the problem (water diversion). Many of the plains fish here live in spring-fed creeks and pools, and USFWS calls water depletion, mainly groundwater pumping for farms, the biggest stressor on the Arkansas darter.

Four of the fish here, the bonytail, Colorado pikeminnow, humpback chub and razorback sucker, are recovered together by that program, a partnership of federal, state, tribal and non-government agencies. The greenback cutthroat trout, Colorado's state fish since 1994, came down to one naturally reproducing population, in Bear Creek. CPW began stocking Bear Creek fry into Herman Gulch in 2016, and in 2022 found young fish there: the stocked trout were reproducing on their own. On the eastern plains, CPW's native fish hatchery in Alamosa breeds six of the small state-listed fish, from the plains minnow to both redbelly daces; in May 2026 more than 18,000 northern redbelly dace went into a creek on the Pawnee National Grassland.

What do these statuses mean? →