It is found in temperate freshwater in North America, from Sonora, Mexico, to British Columbia, Canada.

[5] The Foskett speckled dace, found in "harsh conditions" of the desert waters of the Great Basin spanning parts of Southeastern Oregon and Nevada, has been listed as threatened under the Endangered Species Act since 1985.

Robyn Thorson, the Service's pacific region director, said in a statement; "We attribute this impressive accomplishment to our partners who have worked so hard on the recovery of the dace.

Taxonomy of the Speckled Dace Species Complex (Cypriniformes: Leuciscidae, Rhinichthys) in California, USA.

[7] Speckled dace are the only fish native to all major Western drainage systems from Canada south to Sonora, Mexico.

[3] Studies suggest that even within the Klamath-trinity basin there are three genetically distinct groups which are named after their geographic distribution; Klamath, Trinity, and Jenny.

[9] Canada is the northern limit of the speckled dace's distribution, and there it is found only in isolated parts of the Kettle and Granby Rivers.

During breeding, many males often accompany a single female who broadcasts adhesive eggs over the gravelly stream bed.

The speckled dace arrived in the Los Angeles area streams about 1.9 million years ago.

Speckled Dace native distribution map (orange shading) and the various points represent nonnative records.

Their feeding habits include small invertebrates, especially ones found in riffles such as larvae of hydropsychid caddisflies, mayflies, and midges.

Research argues that when competitive interactions occur in creeks, the speckled dace will inhabit the riffles at the lower end due to their resiliency to a wide range of water temperatures.

[12] Not much is known on the conservation status of speckled dace, but literature suggests most of the subspecies are not listened under the US Endangered Species Act.

[14] Threats to speckled dace include water use from reduced flow during certain seasons due to irrigation and consumption uses, habitat loss potentially through hydro development, industrial land use such as agriculture, and invasive piscivorous fish.

[15] Some specific threats to the R. osculus are reduced flows in the summer and autumn due to irrigation and other consumptive uses, loss of habitat through hydro development, increased siltation and substrate embeddedness from agricultural land clearing and forestry activity, and predation by piscivorous fish.