Habitat Type: Freshwater
Comments: Occurs in many kinds of habitats: riffles, runs, and pools of cool flowing headwaters, creeks, and small to medium rivers with mostly rocky substrates; large and small lakes (rarely); warm, permanent and intermittent streams; and outflows of desert springs (Moyle 1976); usually found in shallow water (averaging about 0.5 m deep or less); in streams, often congregates below riffles and eddies (Minckley 1973). Young tend to occupy edges of streams in slower, shallow water (Cross 1975). Larger adults generally are in relatively quiet water where cover (e.g., overhanging trees, deadfalls, boulders) is available (Minckley 1985).
Stream populations spawn in swift water over rocky substrates. Lake populations spawn in shallow waters with gravel substrate or on gravel edge of riffles in inlet streams (Moyle 1976). In Aravaipa Creek, Arizona, spawning occurred over rapids and riffles, at depths less than 25 cm, over substrates of gravel, cobble, or rubble (Minckley 1981).
Mueller (1984) described spawning behavior of speckled dace in the San Francisco River, New Mexico. Spawning occurred in a 1-m square section of stream recently scoured by human activity. Spawning clusters formed, each with more than 25 fish. Dace thrashed violently (presumable at spawning) and eggs were found at depths to 5 cm. Most eggs were unexposed, attached to undersides of rocks or in interstices between rocks. Territoriality or spawning pairs were not observed.
In the Virgin River (Utah, Arizona, Nevada), speckled dace were collected from 500 m to 1800 m elevation (Cross 1975). Sixty percent were collected in runs, 30 percent in pools, and 10 percent in riffles. Two-thirds of the collections were associated with gravel, rubble, or cobble substrates and one-third with sand and mud. Seventy percent were collected near some type of cover, usually overhanging trees, deadfalls, and boulders. Speckled dace were collected at current speeds averaging 0.43 m/sec (SD = 0.25 m/sec, range 0 to 1 m/sec) and at depths averaging 48 cm (SD = 43 cm).
Speckled dace from the Virgin River (Utah, Arizona, and Nevada) preferred an average temperature of 15.8 C (range 9.5 to 16 C, depending on acclimation temperature) (Deacon et al. 1987). Critical thermal maxima were 30.5, 32.6, and 36.8 C for dace acclimated at 10, 15, and 25 C (Deacon et al. 1987). Rangewide, however, the speckled dace is found at much higher average temperatures, such as 29 C at Ash Meadows, Nevada, 28 C at Pahranagat Valley, Nevada (Deacon and Bradley 1972), and 29.4 C at Kendall Springs in Wyoming (Hubbs and Kuehne 1937).
Lowe et al. (1967) showed that speckled dace, collected from Sonoita Creek, Arizona, were intolerant to elevated temperatures and reduced oxygen levels. Speckled dace were least tolerant to reduced oxygen levels when compared to Agosia chrysogaster, Catostomus clarki, and Cyprinodon macularius (Lowe et al. 1967).