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BC Conservation Data Centre: Species Summary


Rhinichthys osculus
Speckled Dace

 
Scientific Name: Rhinichthys osculus (Girard, 1856)
English Name: Speckled Dace
 
Classification / Taxonomy
Scientific Name - Concept Reference: Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society, Special Publication 20. 183 pp.
Classification Level: Species
Species Group: Vertebrate Animal
Species Code: F-RHOS
Kingdom Phylum Class Order Family
Animalia Craniata Actinopterygii Cypriniformes Cyprinidae
   
Conservation Status / Legal Designation
Global Status: G5 (Sep 1996)
Provincial Status: S3? (May 2019)
BC List: Blue
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status: Endangered (Nov 2016)
SARA Schedule: 1  -  Endangered (Mar 2009)
General Status Canada: 1 - At Risk (2005)
   
Ecology & Life History
General Description: The following description is from Minckley (1973) and Sublette et al. (1990). The speckled dace is a chunky, rounded minnow. Adults reach lengths of 45-80 mm standard length (SL = length from tip of snout to end of hypural plate) (Wallace 1980). Usually there are 8 dorsal rays (6-9), 13-14 pectoral rays, 8 pelvic rays, and 7 anal rays. There are 60-90 scales along the lateral line. The mouth is subterminal, usually with no frenum. Pharyngeal arches contain teeth in two rows, usually 1,4-4,1 or 2,4-4,2. A single, small barbel is located at the edge of each jaw. Coloration is variable depending on geographic location, but often dark and blotchy dorsally, lighter ventrally. A lateral band extends from the dorsal fin onto the caudal peduncle. Breeding males have an intense red color at the base of paired fins, near the anal fin base, on the lower caudal lobe, near the upper part of the gill cleft, and on the mouth. Breeding tubercles are present on pectoral rays of males. Larval speckled dace from the upper and lower Colorado River basin were described by Snyder (1981) and Winn and Miller (1954), respectively.
Global Reproduction Comments: Cross (1975) collected ripe females in late June and mid-July 1973 from the Virgin River drainage in Utah. In Aravaipa Creek, Arizona, speckled dace were collected in breeding coloration or with tubercles from December to August, with mature gonads from November to March, or seen engaged in spawning activities from January to April. Larvae were collected from January to April.

John (1963) studied reproduction in Cave Creek, Chiricahua Mountains, Arizona. Females matured at two years of age. Peaks in reproductive activity were in early spring and late summer. John believed spawning efforts were triggered by flash floods. Males defended territories, and activities of the male often resulted in circular, clean gravel areas that John (1963) called nests. A female entered a defended area and partially buried or wedged herself under the edge of a stone. Males took positions next to the buried female and the pair or group vibrated for a few seconds, after which the female departed. A female entered a nest several times, depositing a portion of her ripe eggs during each spawning event. John (1963) gave data for the total number of eggs laid in an aquarium by each of eight females. From these data, Vives calculated that the number of eggs laid was related to standard length by the equation: number of eggs laid = -264.41 + 10.45 SL (mm) (R- squared = 0.89, p < 0.001). Females ranged from 45 to 75 mm SL and numbers of eggs laid ranged from 174 to 514. Eggs hatched in 6 days at 18 to 19 C under laboratory conditions.

Maximum age of speckled dace in streams of the Chiricahua Mountains is 3 years (John 1964). Moyle et al. (1989) stated that some may live up to 5-6 years.

Females from the Kettle River, British Columbia, Canada, did not mature until the end of their second year (Peden and Hughes 1981).
Global Ecology Comments: Associated with several different faunas depending on location. In the Gila River drainage, native associates include the spikedace (MEDA FULGIDA), roundtail chub (GILA ROBUSTA), loach minnow (TIAROGA COBITIS), longfin dace (AGOSIA CHRYSOGASTER), Sonora sucker (CATOSTOMUS INSIGNIS), desert sucker (CATOSTOMUS CLARKI), and Gila trout (ONCORYNCHUS GILAE). Historical associates included the woundfin (PLAGOPTERUS ARGENTISSIMUS), bonytail (GILA ELEGANS), squawfish (PTYCHOCHEILUS LUCIUS), flannelmouth sucker (CATOSTOMUS LATIPINNIS), and razorback sucker (XYRAUCHEN TEXANUS), all now extirpated from the Gila River basin.

Populations show large fluctuations in size (Minckley 1969, Deacon and Bradley 1972). LaBounty and Minckley (1972) noted that increasing populations of longfin dace may result in decreasing populations of speckled dace in areas of overlap at intermediate elevations. There is not enough data to understand the nature of this relationship (i.e., whether or not it is cause-effect).

Predators include introduced trouts (ONCORHYNCHUS AND SALMO spp.) in the Colorado River mainstream, flathead catfish (PYLODICTUS OLIVARIS) in the Salt River basin, and also introduced basses (MICROPTERUS spp.) and green sunfish (CHAENOBRYTTUS CYANELLUS) (Minckley 1985). THAMNOPHIS CYRTOPSIS (black-necked garter snake) is known to feed on speckled dace (John 1964).

Mpoame and Rinne (1983) recorded the protozoan ICHTHYOPHTHIRIUS MULTIFILIIS, trematode ORNITHODIPLOSTOMUM PTYCHOCHEILUS, and the cestode LIGULA INTESTINALIS as parasites of speckled dace in Aravaipa and Hurricane creeks, Arizona.

Generally occurs in small, loose groups.
Migration Characteristics:
(Global / Provincial)		 
    Nonmigrant:
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant: 		Y /
Y /
N /
na /
Global Migration Comments: Lake populations may migrate short distances up inlet streams to spawn.
Habitats:
(Type / Subtype / Dependence)
Global Habitat 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).
Provincial Habitat Comments: In British Columbia, adults have been found in sections with rock habitat and slow to moderately strong current where siltation and scouring of the river bottom was not excessive (Peden 1984, G. Haas, pers. comm. 1992).
In early spring, adults were found in deep (>1m) runs often in the lee of large rocks, logs and bridge abutments (McPhail 2007). This is likely overwintering behaviour due to low water temperatures (COSEWIC 2006). In July to October, adults are usually found in relatively shallow water (0.1 - 0.65m) in areas with slow surface currents (<0.25m/s) and bottom velocities of 2 cm/s (McPhail 2007).
Juveniles are commonly caught in shallow water (<20cm) in areas of slow current over substrates of coarse gravel or small stones. During freshet, they are often found sheltering in seasonally flooded vegetation (McPhail 2007).
In August, fry were found along the river margins in shallow (<2cm), still water over silt or sand substrates (McPhail 2007).
Food Habits: Herbivore: Adult, Immature
Invertivore: Adult, Immature
Global Food Habits Comments: An omnivorous benthic feeder, at times feeding on drift in mid-water or rarely at the surface (Schreiber and Minckley 1981). The diet consists mostly of benthic insects, also includes other invertebrates, algae, and detritus (little or no plant material or detritus in some areas) (Sublette et al. 1990, Woodbury 1933, Greger and Deacon 1988). Young feed mainly on zooplankton.

Of 97 individuals collected in October from the Columbia River drainage, Canada, 28 percent had consumed only filamentous algae, 39 percent contained only insect remains, and the remaining 33 percent contained algae and insect remains (Peden and Hughes 1981).

Schreiber and Minckley (1981) examined food habits in Aravaipa Creek, Arizona, during January, April, July, and October, 1975, and January 1976. The diet included primarily riffle-dwelling insects, reflecting the association with riffle habitats. Ephemeropteran larvae made up greater than 70 percent of the diet, excepting one sampling period. Plecopteran, trichopteran, and dipteran larvae were used when available

Speckled dace from Little Creek, New Mexico, collected on 18-20 June 1986, consumed primarily dipteran larvae (81 percent by number), ephemeropteran larvae (7 percent), and trichopteran larvae (4 percent) (van Eimeren 1988). At the same location, speckled dace collected on 24-26 October 1986 consumed dipteran larvae (47 percent by number), ephemeropteran larvae (29 percent) and trichopteran larvae (23 percent). Additionally, van Eimeren found little diet overlap between Gila trout and speckled dace even though they shared the same habitats.

Greger and Deacon (1988) examined food habits of speckled dace on 9 February, 20 June, 28 September, and 12 December 1979, in the Virgin River, Utah, Arizona, and Nevada. Dace fed mostly on simuliid larvae in February and June and on chironomid larvae in September and December.
Global Phenology:
Global Phenology Comments: In Lake Tahoe, California, most active at night, inactive during the winter. In New Mexico, feeds primarily between 9:00 p.m. and 1:00 a.m. In streams may be active throughout the year (Moyle 1976). Carter et al. (1986) studied larval drift of upper Colorado River fishes in Colorado from mid-June to September. Speckled dace made up 16-18% of larvae captured. More larvae were captured near shore than midstream. Highest numbers of larvae were captured between 2000 and 0400 h, and lowest numbers between 1600 and 2000 h, suggesting a diurnal pattern of avoidance of daylight.
Provincial Phenology:
(1st half of month/
2nd half of month)
Colonial Breeder: N
Length(cm)/width(cm)/Weight(g): 8/ /
Elevation (m) (min / max): Global: 
Provincial: 
   
 
Distribution
Endemic: N
Global Range Comment: The most ubiquitous fish in the western U.S. (Page and Burr 1991), ranging from the Columbia River drainage (north to southern British Columbia) to the southern Gila River drainage of Arizona and Sonora, Mexico (Peden and Hughes 1981, Minckley et al. 1986, Varela-Romero 1990, Wallace 1980); ecological range extends from small springs of Death Valley to high mountain brooks (Minckley 1985), including waters of the Columbia River basin, Klamath River basin, Oregon lakes, Lahontan basin, Bonneville basin, North-Central basins, Death Valley system, Sacramento River basin, Colorado River basin, and South California Coastal Region (Minckley et al. 1986). [Subspecies osculus was described from Babocomari Creek, Arizona (Girard 1856), but is extirpated there. R. o. osculus now occurs only in about half a dozen locations, including Aravaipa Creek, Cave Creek (Chiricahua Mountains), Redfield Canyon, and Sonoita Creek, Arizona (Minckley 1981, Minckley 1991).]
 
Authors / Contributors
Global Information Author: Hammerson, G.
Last Updated: Dec 08, 1995
Provincial Information Author: CANNINGS, S.G.
Last Updated: May 01, 1992
   
References and Related Literature
Andersen, M. E., and J. E. Deacon. 1996. Status of endemic non-salmonid fishes in eastern Nevada. Journal of the Arizona-Nevada Academy of Science 29:124-133.
B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC.
COSEWIC. 2002g. COSEWIC assessment and update status report on the speckled dace Rhinichthys osculus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 36 pp.
COSEWIC. 2006x. COSEWIC assessment and update status report on the speckled dace Rhinichthys osculus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 27pp.
Courtenay, W. R., Jr., J. R. Deacon, D. W. Sada. R. C. Allan and G. L. Vinyard. 1985. Comparative status of fishes along the course of the pluvial White River, Nevada. Southwestern Naturalist 30(4):503-524.
Lee, D. S., C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. 1980. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, North Carolina. i-x + 854 pp.
McPhail, J.D. 2007. The freshwater fishes of British Columbia. The University of Alberta Press, Edmonton, Alberta.
Miller, R. R., J. D. Williams, and J. E. Williams. 1989. Extinctions of North American fishes during the past century. Fisheries 14(6):22-38.
Minckley, W. L. 1973. Fishes of Arizona. Arizona Game and Fish Department, Phoenix, Arizona. 293 pp.
Moyle, P. B. 1976a. Inland fishes of California. University of California Press, Berkeley, California. 405 pp.
Moyle, P. B., J. E. Williams, and E. D. Wikramanayake. 1989. Fish species of special concern of California. Final report submitted to California Dept. of Fish and Game, Inland Fisheries Division, Rancho Cordova. 222 pp.
Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes: North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.
Peden, A.E., and G.W. Hughes. 1984. Status of the speckled dace, Rhinichthys osculus, in Canada. Can. Field-Nat. 98:98-103.
Peden, A.E., and G.W. Hughes. 1988. Sympatry in four species of Rhinichthys (Pisces), including the first documented occurrences of Rhinichthys umatilla in the Canadian drainages of the Columbia River. Canadian Journal of Zoology 66(8):1846-1856.
Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society, Special Publication 20. 183 pp.
Scott, W. B., and E. J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada, Bulletin 184. 966 pp.
Sigler, W. F., and R. R. Miller. 1963. Fishes of Utah. Utah State Department of Fish and Game, Salt Lake City, Utah, 203 pp.
Sublette, J. E., M. D Hatch, and M. Sublette. 1990. The fishes of New Mexico. University New Mexico Press, Albuquerque, New Mexico. 393 pp.
Taylor, F. R., L. A. Gillman, and J. W. Pedretti. 1989. Impact of cattle on two isolated fish populations in Pahranagat Valley, Nevada. Great Basin Naturalist 49:491-495.
Troffe, P. 1999. Freshwater Fishes of the Columbia Basin. Royal B.C. Mus. 102pp.
U.S. Fish and Wildlife Service (USFWS). 18 September 1987. Proposed endangered status for Independence Valley speckled dace and Clover Valley speckled dace. Federal Register 52:35282-35286.
U.S. Fish and Wildlife Service (USFWS). 1982. Emergency determination of endangered status for two fish species in Ash Meadows, Nevada. Federal Register 47(90):19995-19999.
U.S. Fish and Wildlife Service (USFWS). 1990. Endangered and threatened species recovery program: report to Congress. 406 pp.
Williams, J. E. and D. W. Sada. 1985b. Status of two endangered fishes, Cyprinodon nevadensis mionectes and Rhinichthyes osculus nevadensis, from two springs in Ash Meadows, Nevada. Southwestern Naturalist 30:475-84.
Williams, J. E., M. A. Stern, A. V. Munhall, and G. A. Anderson. 1990. Conservation status of threatened fishes in Warner Basin, Oregon. Great Basin Naturalist 50(3):243-8.
Wydoski, R. S., and R. R. Whitney. 1979. Inland fishes of Washington. The University of Washington Press, Seattle. 220 pp.
 

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 1995. Species Summary: Rhinichthys osculus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 6, 2025).