Grand Canyon was once home to eight species of native fish. Only five of these species are found in the park today. Following the completion of Glen Canyon Dam in 1963, the fish assemblage in the Colorado River in Grand Canyon has shifted to non-native rainbow and brown trout in the stretches of river closest to the dam and above the Little Colorado River.
Grand Canyon has a very distinctive collection of native fish. All eight native species belong to only two families: minnows (Cyprinidae) and suckers (Catostomidae). Six of the eight native species are found only in the Colorado River basin. This very high percentage of endemic fish species likely results from the geographic isolation of the Colorado River system, and the highly variable natural environments, flow and temperature regimes of the river and its tributaries.
Grand Canyon National Park is currently conducting a variety of projects to conserve and restore native fish populations, especially the endangered humpback chub. The National Park Service is also developing plans to determine the status of the razorback sucker, an endangered species thought to be extirpated from Grand Canyon until 2012, when several individuals were detected in the western reaches of the Colorado River close to Lake Mead.
Last updated: February 14, 2021