Habitat for the Owens pupfish consists of spring pools, sloughs, irrigation ditches, swamps, and flooded pastures in the Owens Valley from Fish Slough in Mono County to Lone Pine in Inyo County. Currently, this fish is confined to five populations in the Owens Valley.
Less than 2.5 inches in length, the Owens pupfish is a small, deep-bodied, laterally compressed fish. Males are larger and deeper bodied than females. Breeding males are bright blue with broad vertical bars on the side. Females are generally brownish above and silvery below, with several irregular brownish vertical bars. Non-breeding males resemble females. Owens pupfish congregate in small schools and feed mostly on aquatic insects. Reproduction occurs from January through September. Spawning occurs in male-defended territories. Females may spawn daily, laying a few eggs at a time.
Historically, Owens pupfish occurred in the Owens River and spring pools, sloughs, irrigation ditches, swamps, and flooded pastures in the Owens Valley from Fish Slough in Mono County to Lone Pine in Inyo County. Habitat alteration associated with the introduction of non-native trout and bass, along with historic water resources development reduced the distribution and abundance of this species. Currently, this fish is confined to five populations in the Owens Valley.
The Fish Slough ACEC is a system of springs and marshes cooperatively managed by the Department, BLM, Los Angeles Department of Water and Power (LADWP), University of California Natural Reserve System, and USFWS. Two sites within Fish Slough, 'BLM Spring' and the Owens Valley Native Fishes Sanctuary, have lost pupfish populations following illegal introductions of largemouth bass. BLM Spring was restored in with BLM in 2002, and reintroduction of pupfish occurred in 2003. This project included dam reconstruction, fabrication/installation of a new type of fish migration barrier, vegetation control, and exotic fish removal. Two additional populations tenuously persist in marshy areas of Fish Slough. Pupfish also occur in Inyo County at Mule Spring on BLM land, at Warm Springs and below an artesian well on LADWP land.
(Excerpted from DFG publication, Species Accounts - Fish (PDF)