Common Name: Loach Minnow

Scientific Name: Rhinichthys cobitis

 Appearance: The Loach Minnow is a small stream dwelling minnow, with a maximum length of about 2.75 inches. The body is elongated, and a little compressed and flattened vertically, particularly towards the head. Mouth is small, terminal, and highly oblique with no barbels present. Upper lip is non-protractile and attached to the snout by a broad fold of tissue (Minckley 1973).

Loach minnow have an olivaceous background coloration highly blotched with darker pigment. Whitish spots are present at the origin and insertion of the dorsal fin as well as the dorsal and ventral portions of the caudal fin base. A black basicaudal spot is usually present. Breeding males develop bright red-orange coloration on the lips, at the bases of fins, and often on abdomen. Breeding females become yellowish in color on their fins and lower body (Minckley 1973).  Distinguished from the similar Speckled Dace by whitish spots present on the origin and insertion of the dorsal fin and on the dorsal and ventral portions of the caudal fin base.

 

Male Loach Minnow with spawning colors, captured in Campbell Blue Creek.

Diet: Loach minnow are opportunistic benthic insectivores, feeding mainly upon riffle-dwelling larval ephemeropterans (mayflies), simuliid dipterans (black flies), and chironomid dipterans (non-biting midges). They actively seek their food among bottom substrates, rather than pursuing items in the drift.

Habitat and Range: The cryptic, solitary, and sedentary loach minnow occupies turbulent, rocky riffles of rivers and smaller streams. They prefer moderate to swift current velocity and gravel or cobble substrates. They are sometimes associated with dense, filamentous green algae. Loach Minnow is restricted almost exclusively to a bottom dwelling habitat because of a reduced gas bladder.

Endemic to Gila River Basin. Historically were distributed near and upstream of Phoenix, in the Gila, Agua Fria, Salt, San Pedro, and Verde River systems in Arizona. They were also found in New Mexico, and Sonora, Mexico. Occupied streams ranged in elevation from about 2,300 – 8,200 ft.  Today they are limited to about eight natural populations in Arizona and New Mexico.

Historical locations (dots) of Loach Minnow in Gila River basin streams.

Breeding: Spawning occurs late winter to the beginning of summer, depending on elevation of the stream. First spawn occurs in their second year. They spawn in the same riffles that they occupy during the non-reproductive season.  They find or dig nest cavities on the underside of flattened rocks, with the nest entrance facing downstream.  The female lays adhesive eggs on the underside of the rock.  The male, and possibly the female, guards the nest cavity.  The number of eggs per rock ranges from 5 to more than 250, but typically is 52 to 63 (Marsh 1991). Eggs hatch in five to six days.

Status: Federally listed as Endangered with critical habitat in 2012.

Threats: Altered flow hydrology; dams and water diversions; altered habitat; and predation by and competition with nonnative fishes.

Actions: The Arizona Game and Fish Department, New Mexico Department of Game and Fish, U.S. Fish and Wildlife Service, U.S. Bureau of Reclamation, U.S. Forest Service, U.S. Bureau of Land Management, universities and private organizations have been working together as part of the Loach Minnow Recovery Team and Loach Minnow Conservation Team to protect and restore Loach Minnow throughout their historic range. Actions have included barrier construction to prevent upstream migration of nonnative fish into Loach Minnow occupied reaches, the reintroduction of Loach Minnow to streams in the species range, and removing nonnative fish species.  A few new populations have been established but finding new locations for reintroductions is challenging because of drying climate and widespread non-native fishes.

Biologists prepare to stock Loach Minnow in Fossil Creek; 2007.

Additional Resources:

Marsh, P.C. 1991. Loach Minnow, Tiaroga cobitis Recovery Plan; for Region 2, U.S. Fish and Wildlife Service, Albuquerque, New Mexico. Arizona State University, Tempe, Arizona. pp. i-38.

Minckley, W.L. 1973. Fishes of Arizona. Arizona Game and Fish Department, Phoenix. pp. 133-135.

USDI, Fish and Wildlife Service. 2012. Endangered and Threatened Wildlife and Plants;

Endangered Status and Designations of Critical Habitat for Spikedace and Loach Minnow. Federal Register 77(36):10810-10932.