The Warner sucker (Catostomus warnerensis) is a rare species of freshwater ray-finned fish in the family Catostomidae.

Native to Oregon in the United States and found only in the Warner Basin, its distribution extends just into Nevada[2] and California.

[3] Threats to the species include the many dams which have been installed in the local creeks to divert water for agriculture.

[1] Conservation efforts include the restoration of riparian vegetation and the construction of a fishway at a dam on a major creek.

Individuals have been transplanted to Summer Lake Wildlife Management Area when they were threatened by drought conditions; these fish died but not before successfully reproducing in their new habitat.

[3] Conservation activities in the area have been shown to benefit the Great Basin redband trout (Oncorhynchus mykiss newberrii) as well as the sucker.