About the Endangered Fish

The Upper Colorado River Basin is home to 14 native fish species, including the endangered humpback chub, bonytail, Colorado pikeminnow, and razorback sucker. These endangered fish are found only in the Colorado River system.

Humpback Chub (Gila cypha)
The humpback chub is a big-river minnow found only in canyon sections of the Colorado River Basin. It was first listed as endangered in 1967 and was given full protection under the Endangered Species Act in 1973. There are six known populations with the largest in the Grand Canyon. The other populations are above Lake Powell in the Upper Colorado River Basin. Individuals may reach 20 inches in length and live 30 years. Adults are capable of reproducing at 2 to 3 years of age, and spawning occurs in spring and early summer. Humpback chub feed on insects, plankton, and plant matter.

Bonytail (Gila elegans)
The bonytail is a big-river minnow that was historically common throughout the Colorado River Basin. It was listed as endangered and given full protection under the Endangered Species Act in 1980. This is the rarest of the four endangered Colorado River fish species and wild populations no longer exist. Individuals may reach 22 inches in length and live 50 years. Adults are capable of reproducing at 2 to 3 years of age, and spawning probably occurred in spring and early summer. Bonytail feed on insects, plankton, and plant matter. The species is being reintroduced into the Green, and upper Colorado rivers, Lakes Mojave and Havasu, and the lower Colorado River to Yuma, Arizona.

Colorado Pikeminnow (Ptychocheilus lucius)
The Colorado pikeminnow is a big-river minnow found only in the Colorado River Basin. It was first listed as endangered in 1967 and was given full protection under the Endangered Species Act in 1973. Valued as food by early settlers and miners throughout the basin, wild populations now only occur in rivers upstream of Glen Canyon Dam, Arizona, and are stable or increasing. Individuals may reach 6 feet in length, weigh 80 pounds, and live 40 years. Known for long-distance spawning migrations of more than 200 miles in late spring and early summer, adults are capable of reproducing at 5 to 7 years of age. Young Colorado pikeminnow feed on insects and plankton, whereas adults feed mostly on fish. The species is being reintroduced into the San Juan and Verde rivers.

Razorback Sucker (Xyrauchen texanus)
The razorback sucker is a big-river fish found only in the Colorado River Basin. It was listed as endangered and given full protection under the Endangered Species Act in 1991. Valued as food by early settlers and miners, wild populations of razorback sucker are now extremely rare, declining, and consist primarily of adults. Poor survival of young has been attributed to loss of habitat and predation by nonnative fishes. Individuals may reach 36 inches in length, weigh 14 pounds, and live 40 years. Adults are capable of reproducing at 3 to 4 years of age, and spawning occurs during high spring flows. Razorback sucker feed on insects, plankton, and plant matter. The species is being reintroduced into the Green, Gunnison, upper Colorado and San Juan rivers, Lakes Mojave and Havasu, and the lower Colorado and Verde rivers.

Historical perspective
Learn more about the endangered Colorado River fishes through the experiences of those who observed them firsthand during the early 20th century.