Montana Field Guide

The Black Carp is a large cyprinid, often exceeding 1 meter (3 feet) long. The maximum reported size is approximately 2m TL and 70kg (Nico et al. 2005). Body shape of the Black Carp species is stout, elongate, and cylindrical to slightly compressed with a short and relatively deep caudal peduncle (Nico et al. 2005). From 39-46 relatively large scales can be observed along the lateral line (Nico et al. 2005). Although body coloration can be variable, most individuals are dark brown or blue-grey with darkly pigmented fins (Nico et al. 2005). Black Carp have a relatively short head, moderate size eyes, and a slightly rounded snout (Nico et al. 2005). Black Carp have a relatively small to moderate size mouth which is placed terminally or sub-terminally with no barbels present (Nico et al. 2005). Gill rakers of Black Carp are short, stout, and range from 14-21, with most accounts ranging from 18-21 (Nico et al. 2005). The anal fin and short dorsal fin both have 7-9 rays, the caudal fin is large and forked, and the dorsal fin origin is slightly anterior to the pelvic fin origin (Nico et al. 2005). During the reproductive season, male Black Carp develop breeding or nuptial tubercles, although these may be hard to observe sometimes (Bardach et al. 1972). Breeding tubercles have been reported on the interorbital region, pectoral-fin rays, operculum, and sides of the body (Kimura and Tao 1937; Wu et al 1964b; Chang 1966; Zhong et al. 1980). Tubercles are absent in females (Chang 1966).

Morphologically, the black carp is most similar in external appearance to grass carp. However, the black carp is typically darker and has a more pointed snout and a more subterminal mouth. The most reliable character distinguishing this species is the pharyngeal apparatus. In black carp, this structure is heavily muscled and armed with large molariform teeth that, in combination with a large chewing pad, crushes and masticates the shells of mollusks to extract soft tissues (Nico et al. 2005). Pharyngeal teeth generally form a single row of four or five large molariform teeth per side, and an outer (secondary) row is present sometimes, consisting of a single tooth (possibly two in rare instances) on one or both sides (Nico et al. 2005). Juvenile and adult Black Carp (31-330 mm TL) pass through several generations of pharyngeal teeth, the pharyngeal teeth may be conical in small Black Carp (<30mm TL) (Liu et al. 1990). The dentition formula for this species is typically 0,4-5,0 or 1,4-4,1 (Nico et al. 2005).

Migrates upriver and spawns in open water during flood phase, eggs are pelagic or semipelagic and hatch while drifting downstream, larvae then migrate into floodplain lakes and channels with little or no current (Kottelat and Freyhof 2007; Soin and Sukhanova 1972). If the river flow is blocked or if available river stretches are too short, eggs cannot drift long enough and will not develop (Kottelat and Freyhof 2007). Both migration and spawning activities are initiated in response to a combination of physical and hydrologic changes, such as increasing water levels, flows, and water temperature (Yih and Liang 1964; Jennings 1988; Opuszynski and Shireman 1995). However, the importance of any one factor may vary among different regions (Nico et al. 2005). Humans have greatly contributed to the movements of this species through aquaculture pond releases (Nico et al. 2005).

This species can be found in rivers, streams, or lakes; however, it requires large rivers to reproduce (Nico et al. 2005). The typical habitat includes reaches of large rivers that are below 200 m above sea level (Li and Fang, 1990), such as channels of lowland rivers and associated floodplain lakes and backwaters. The species also occurs in artificial habitats (including canals), and some populations survive in lakes and reservoirs, although reproduction and completion of their life cycle require a connection to flowing waters (Nico and others, 2005).

The black carp is a bottom-dwelling molluscivore that has been used by U.S. fish farmers to prey on and control disease-carrying snails in their farm ponds (Nico and Nielson 2018).

The black carp is a bottom-dwelling molluscivore that has been used by U.S. fish farmers to prey on and control disease-carrying snails in their farm ponds (Nico and Nielson 2018). The typical habitat includes reaches of large rivers that are below 200 m above sea level (Li and Fang 1990), such as channels of lowland rivers and associated floodplain lakes and backwaters. The species also occurs in artificial habitats (including canals), and some populations survive in lakes and reservoirs, although reproduction and completion of their life cycle require a connection to flowing waters (Nico et al. 2005). The species is tolerant of temperatures from about 0.5-40 °C (Nico et al. 2005). The Black Carp is known to occasionally inhabit the deltas of rivers (for example, Yangtze River, China), where it may encounter brackish waters (Nico et al. 2005). The species is tolerant of pH from 6-10 for limited periods of time; however, the preferred range is from 7 or 7.5-8.5 (Nico et al. 2005). Black Carp is tolerant of oxygen levels as low as 2 mg/L. Larvae and small juveniles feed almost entirely on small invertebrates (such as zooplankton and aquatic insects) (Nico et al. 2005). Larger juveniles and adults are bottom feeders that predominantly prey on snails and bivalve mollusks, although crayfish and other benthic invertebrates are sometimes consumed (Nico et al. 2005). The heavy pharyngeal arches and large molariform teeth of Black Carp are adapted to crush mollusk shells (Liu et al. 1990; Nico et al. 2005). There is high potential that the black carp would negatively impact native aquatic communities by feeding on, and reducing, populations of native mussels and snails, many of which are considered endangered or threatened (Nico et al. 2005). Given their size and diet preferences, black carp have the potential to restructure benthic communities by direct predation and removal of algae-grazing snails (Nico et al. 2005).

Reproduction takes place in late spring and summer when water temperatures and/or water levels rise (Nico et al. 2005). Reproduction and egg development generally occur between 18-30 °C. Both male and female black carp are broadcast spawners; females are capable of releasing hundreds of thousands of eggs into flowing water, which then develop in the pelagic zone (Nico et al. 2005). After fertilization, the eggs become semi-bouyant (Sukhanova, 1967 as cited in Nico et al. 2005). They hatch in 1 to 2 days, depending on water temperatures, and the yolk sac is absorbed in 6 to 8 days (Nico et al. 2005). They become sexually mature at 4 to 6 years after which they migrate back to their spawning grounds (Nico et al. 2005). Successful reproduction is known only from riverine habitats (Nico et al. 2005). Their lifespan probably exceeds 15 years (Biro 1999). Specific spawning habitat may be needed, since black carp eggs are non-adhesive and semi-buoyant, requiring current to keep them from sinking to the bottom. The eggs and larvae are carried into floodplain lakes, smaller streams, and low-current channels that serve as nursery areas for larval and juvenile black carp (Conover et al. 2007). Reproduction in the Mississippi River has not been documented, but new information and recent collections suggest the species is likely established in the lower part of the Mississippi Basin and possibly elsewhere in the basin (Nico et al. 2005). Hybrids in nature have not been reported. However, the Black Carp has been artificially crossed (with limited success) with Grass Carp, Silver Carp, Bighead Carp, Common Carp, and Black Bream (Ryabov 1979; Evtushenko et al. 1994; Biro 1999; Nico et al. 2005).

The species is tolerant of temperatures from about 0.5-40 °C (Nico et al. 2005). The Black Carp is known to occasionally inhabit the deltas of rivers (for example, Yangtze River, China), where it may encounter brackish waters (Nico et al. 2005). The species is tolerant of pH from 6-10 for limited periods of time; however, the preferred range is from 7 or 7.5-8.5 (Nico et al. 2005). Black Carp is tolerant of oxygen levels as low as 2 mg/L.

Because of the range of temperatures, pH and oxygen levels that this species can tolerate, it is likely that an introduction into the large river systems of Montana (Yellowstone or Missouri Rivers) would result in a sustaining population that could detrimentally affect the aquatic ecosystem.

There is high potential threat that the black carp would negatively impact native aquatic communities by feeding on, and reducing populations of native mussels and snails, many of which are considered endangered or threatened (Nico et al. 2005).