endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Native to main Sacramento-San Joaquin river system, Pajaro-Salinas river drainage, and Clear Lake, California. Apparently introduced into the Russian River drainage, California. Introduced into the Carmel River drainage, California, and the Truckee Meadows area, west-central Nevada. Introduced and abundant in Lahontan Reservoir on Carson River, western Nevada, and possibly elsewhere. Common within native range (abundant in Clear Lake) (Page and Burr 1991).
Length: 45 cm
Habitat and Ecology
Habitat Type: Freshwater
Comments: Typically found in warm, shallow, turbid waters, where current slight or absent, including reservoirs and small to large rivers (Moyle 1976, Page and Burr 1991). In oxbows and similar nutrient rich waters of Delta. High tolerance for low oxygen conditions. Young school near shore, adults in open water away from shore. Spawns in warm, shallow water in areas heavily vegetated with aquatic plants (Moyle 1976).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Comments: Feeds mainly on planktonic algae and zooplankton (e.g., rotifers, cladocerans, copepods, detritus) (Moyle 1976). Appears to be mainly a herbivorous filter-feeder.
Life History and Behavior
Mature by 2nd or 3rd year. Spawning occurs April-July, at water temperatures of 12-24 C.
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Total adult population size is unknown but relatively large.
Trend over the past 10 years or three generations is uncertain but likely relatively stable or slowly declining.
Comments: Localized threats may exist, but on a range-wide scale no major threats are known.
Relevance to Humans and Ecosystems
Comments: A commercial fishery centered around the Chinese-American food trade has long existed for this species (McGinnis 1984).
Blackfish are distinctive for their overall dark color (thus the common name). Younger individuals are more silvery, but darken as they age. The scales are unusually small, counting 90-114 along the lateral line. The forehead has a straight-line profile, the eyes are smallish, and the terminal mouth slants upwards. The dorsal fin starts just behind the pelvic fins, and has 9-11 rays, while the anal fin has 8-9 rays, and the pelvic fins 10 rays. The pharyngeal teeth are long, straight, and knife-shaped; the dorsal part of each tooth has a narrow grinding surface. They have been recorded at up to 55 cm in length.
Unlike most North American cyprinids, they feed on zooplankton, planktonic algae, and floating detritus, including rotifers, copepods, cladocerans, diatoms, and the like. Younger fish pick at food items individually, while adults work by pumping large amounts of water through the oral cavity; the food bits are caught in a patch of mucus on the roof of the mouth, where it is secreted by a special organ, and then the fish swallows mucus and food together.
Blackfish are primarily denizens of the warm turbid waters found on the floor of the Central Valley, such as sloughs and oxbow lakes connected to the Sacramento and San Joaquin Rivers. They are also common in Clear Lake, Pajaro River, Salinas River, the small creeks that feed into San Francisco Bay. A population is present in the Russian River, although they may have been introduced. They also thrive in reservoirs, and have been spread to a number of California reservoirs via the California Aqueduct, and into Nevada via the Lahontan Reservoir (1964) where they have further colonized the Humboldt River drainage.
Sacramento blackfish are of some commercial significance, and are sold live at many Asian fish markets in California.
Names and Taxonomy
Comments: Monotypic and very distinctive from other endemic minnows. Hybridizes with LAVINIA EXILICAUDA and GILA BICOLOR (Lee et al. 1980).