Tough Fish in a Harsh Place: Red Hills Roach

by Peter B. Moyle


Red Hills roach. The upper fish is about 60 mm (2.5 inches) total length. Photo by P. Moyle

Red Hills Roach are small (adults are 60-70 mm in total length) bronzy minnows that live in a challenging environment. They survive in a few small streams that start as seeps in a hot dry landscape, the serpentine outcrops of the Red Hills, at about 1200 ft in elevation (Tuolumne County).  The streams flow through a hot landscape in summer, only lightly shaded, and a pool with more than a foot of water is regarded as deep.  The water of the streams is likely laced with magnesium, iron, and other minerals leached from the serpentine deposits.  Because the land through which the streams flow is of low value, in the past it had been mined, heavily grazed, and run-over by off-road vehicles. The region is now managed by the Bureau of Land Management (BLM) as the Red Hills Recreation Management Area.  Of the 11 varieties of fish that are labeled as roach (Hesperoleucus), the Red Hills roach has the most restricted distribution, so is the most vulnerable to extinction (see California water blog for February 10, 2019; Baumsteiger and Moyle 2019).

My guess is that the Red Hills roach has survived mainly because BLM designated part of their habitat as an Area of Critical Environmental Concern, which was established to protect rare species of plants that mainly grow on serpentine soils. The plants include the purple-flowered California verbena (Verbena californica) that, like the roach, is found only the Red Hills, in association with seeps that feed the stream. By protecting the native plants, the managers also protected the only species of vertebrate that is endemic to a serpentine-dominated landscape: the Red Hills Roach, Hesperoleucus symmetricus serpentinus.  This is a classic endangered species, a small, ordinary-looking fish with a peculiar common name, for a fish, which is followed by a very long, if somewhat poetic, scientific name (try saying it out loud a few times). It is perhaps appropriate that this unusual California fish is associated with the official state rock, serpentine.


Red Hills Roach Habitat, July 15, 2010. Photo by P. Moyle.

For a good description of the Red Hills geology, flora, and fauna see the Wikipedia account. To get a good idea of the habitat of the Red Hills roach watch the video that was filmed and narrated in 2015 by Kit Tyler (5 minutes):

Also read Amber Manfree’s blog account of the search for Red Hills roach (and other roaches) during the last drought.


The Red Hills roach is currently listed as a Fish Species of Special Concern by the California Department of Fish and Game based on its limited distribution (1-2 km of small stream) and small population (<500 adults).  The CDFW account also provides a description of threats to the fish and well as recommended management actions.

Now that the Red Hills roach has a formal scientific name, it should be listed as both a state and federal threatened species, with the extra protection such designations provide.  Moyle et al (2011) rated its status as of High Concern (status score of 2.1 on a scale of 1.0-5.0), while it was rated as “critically vulnerable” to extinction because of climate change by Moyle et al. (2013).

Map of RHR

Map of the Six-bit Gulch watershed, which drains the Red Hills.  The Red Hills roach is found primarily in the upper half of the gulch.  The lower reaches and headwaters are typically dry in summer.  Map by Amber Manfree.

Further reading

Baumsteiger, J. and P. B. Moyle. 2019. A reappraisal of the California Roach/Hitch (Cypriniformes, Cyprinidae, Hesperoleucus/Lavinia) species complex. Zootaxa 4543 (2): 2221-240.  (available as open-access download).

Moyle, P.B., J. V. E. Katz and R. M. Quiñones.  2011. Rapid decline of California’s native inland fishes: a status assessment.  Biological Conservation 144: 2414-2423.

Moyle, P.B., J. D. Kiernan, P. K. Crain, and R. M. Quiñones. 2013. Climate change vulnerability of native and alien freshwater fishes of California: a systematic assessment approach. PLoS One.

Moyle, P.B., R. M. Quiñones, J.V.E. Katz, and J. Weaver. 2015.  Fish Species of Special Concern in California.  3rd edition.  Sacramento: California Department of Fish and Wildlife.

Peter B. Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences.


Left: typical habitat, 2014, photo by M. Ogaz.; Right: Jacob Katz, Red Hills Roach habitat, 2010,photo by P. Moyle.

About jaylund

Professor of Civil and Environmental Engineering Director, Center for Watershed Sciences University of California - Davis
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