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Hypophthalmichthys molitrix (Valenciennes, 1844) Silver carp |
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photo by
Ramani Shirantha |
| Family: | Xenocyprididae (East Asian minnows) | |||
| Max. size: | 120 cm TL (male/unsexed); max.weight: 50 kg; max. reported age: 20 years | |||
| Environment: | benthopelagic; freshwater; brackish; depth range 0 - 20 m, potamodromous | |||
| Distribution: | Asia: Native to most major Pacific dainages of East Asia from Amur to Xi Jiang, China (Ref. 59043) and Hanoi, Vietman (Ref. 120939). Introduced around the world for aquaculture and control of algal blooms. Several countries report adverse ecological impact after introduction (Ref. 1739). Often confused with Hypophthalmichthys nobilis (Ref. 59043). | |||
| Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 7-10; Anal spines: 0-0; Anal soft rays: 11-17. Diagnosis: Body olivaceous to silvery. Barbels absent. Keels extend from isthmus to anus. Edge of last simple dorsal ray not serrated. Branched anal rays 12-13.5 (Ref. 13274). It differs from Hypophthalmichthys nobilis by having sharp scaleless keel from pectoral region to anal origin, 650-820 long, slender gill rakers, head length 24-29% of standard length, and plain pale coloration, greenish grey above, whitish below (Ref. 59043). Description: Body club-shaped (Ref. 52193). Large head; mouth small, upturned; eyes set low, below the level of the mouth; gill rakers attached to each other to form a sieve; intestine extended (Ref. 52193). Dorsal fin with 3 unbranched and 7 branched rays; anal fin with 3 unbranched and 12 branched rays; pelvic fins in front of origin of dorsal fin (Ref. 52193). Scales minute; 110-115 scales in lateral line (Ref. 52193). Colouration: Body olivaceous to silvery (Ref. 40476) |
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| Biology: | Found in their natural range in rivers with marked water-level fluctuations and overwinters in middle and lower stretches, swimming just beneath the surface. They feed in shallow (0.5-1.0 m deep) and warm (over 21°C) backwaters, lakes and flooded areas with slow current on phytoplankton and zooplankton (Ref. 30578, 10294). Bigger individuals from about 1.5 cm SL feed only on phytoplankton while larvae and small juveniles prey on zooplankton (Ref. 59043). Adults breed in rivers or tributaries over shallow rapids with gravel or sand bottom, in upper water layer or even at surface during floods when the water level increases by 50-120 cm above normal level. Conditions for spawning include high current (0.5-1.7 m/s), turbid water, temperatures above 15°C (usually 18-26°C) and high oxygen concentrations (Ref. 59043). Spawning ceases if conditions change (especially sensitive to water-level fall) and resumes again when water level increases. Juveniles and adults form large schools during spawning season. Mature individuals undertake long distance upriver migration at start of a rapid flood and water-level increase, able to leap over obstacles up to 1 m. After spawning, adults migrate to foraging habitats, In autumn, adults move to deeper places in main course of river where they remain without feeding. Larvae drift downstream and settle in floodplain lakes, shallow shores and backwaters with little or no current (Ref. 59043). In aquaculture, it can survive brackish water (up to 7 ppt) when released into estuaries and coastal lakes (Ref. 59043). Escape from fish farms are widely known even as they are stocked in large rivers and almost all still water bodies like lakes and ponds. Utilized fresh for human consumption and also introduced to many countries where its ability to clean reservoirs and other waters of clogging algae is appreciated even more than its food value (Ref. 9987). One of among 3 or 4 species of cyprinids whose world production in aquaculture exceeds 1 million tons per year (Ref. 30578). | |||
| IUCN Red List Status: | Near Threatened (NT); Date assessed: 20 January 2011 Ref. (130435) | |||
| Threat to humans: | potential pest | |||