Taxonomic name: Channa argus (Cantor, 1842)
Synonyms: Channa argus argus, Ophicephalus argus, Ophicephalus nigricans, Ophicephalus pekinensis
Common names: amur snakehead (English), eastern snakehead (English), ga mul chi (Korean), kamuruchi (Japanese), northern snakehead (English), ocellated snakehead (English), raigyo (Japanese), zmeegolov (Russian)
Organism type: fish Little is known of the impacts of the northern snakehead (Channa argus), but as a voracious top-level predator with no natural enemies, its introduction could interrupt and devastate the food web of freshwater systems. Although it can live outside the water for up to 4 days, biologists believe that C. argus is not well adapted to land travel. The major threat of dispersal is through human release. Description
C. argus has a torpedo-shaped body that tapers towards the tail. Young are golden brown to pale gray in colour, turning dark brown and developing black splotches as they age. Other distinguishing characteristics are long dorsal and anal fins, small head, and large mouth. Adults can grow up to 1.2 metres long and weigh up to 15 pounds. Occurs in:
lakes, water courses, wetlands Habitat description
C. argus inhabits freshwater with a temperature range of 0 to 30°C. It has been found in swamps, shallow ponds, and slow moving streams with vegetated or muddy substrate. Although C. argus is not well adapted to land travel, it can survive out of water up to four days breathing oxygen. General impacts
C. argus could cause devastation to freshwater ecosystems of the United States because of its predacious nature, lack of natural predators, high fertility, and adaptability to a wide range of environmental conditions. Where introduced, it could bring disease and harm native organisms. These changes could also hurt local economies dependent on fishing (Courtenay, W., pers. comm., 2003). Uses
C. argus is imported and sold in live food trade markets around the world as a food source for human consumption. Notes
A subspecies C. argus argus is common in China and Korea. Another subspecies, C. argus warpachowski, is found in the Amur River of Russia and China. "In the 1960s it was introduced into the Aral Sea basin and has become widespread in that basin's rivers" (Hilton, 2002). Geographical range
Native range: C. argus is native to China and Korea.
Known introduced range: It has been found in Japan, western Asia, eastern Europe, and 5 states in the United States. Introduction pathways to new locations
Live food trade: Snakeheads are imported for food but it seems that surplus fish are sometimes released into the environment for a variety of reasons.
Local dispersal methods
Natural dispersal (local): The snakehead may move in stream and river networks, reproducing and spreading to adjacent watersheds.
Other (local): Direct intentional release by members of the public of these fish into freshwater locations appears to be the most probable introduction mechanism (Carlton, J., pers. comm., 2002). Management information
Preventative measures: C. argus (and all snakeheads) were banned from importation and interstate transport in the USA in October 2002 (Courtenay, W., pers. comm., 2003).
Chemical: In Crofton pond, Maryland, USA, herbicides (Diquat Dibromide and Glyphosate) were used to lower oxygen levels, then a piscicide (Rotenone) was used to poison the fish (Hilton, 2002). Eradication would be much more complicated in rivers, streams, or larger lakes. Nutrition
Young C. argus eat zooplankton. At a length of about 18mm, they begin to eat fish larvae and small crustaceans. Adults prefer fish but will eat frogs, crustaceans, and even small reptiles, birds, and mammals. They remain close to shore, typically under aquatic vegetation, and are most active at dusk and dawn, feeding very near the shore (Courtenay, W., pers. comm., 2003). Reproduction
Parents guard the young until they are approximately 18mm in length. C. argus spawns 1 to 5 times a year and lays 1,300 to 15,000 eggs per spawn. Lifecycle stages
C. argus matures at 2 years when it is approximately 30cm in length and spawns in June or July in its native range. Reviewed by: Dr. Walter R. Courtenay, Research Fishery Biologist, Center for Aquatic Resources Studies, USGS Florida Integrated Science Centers.
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
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Last Modified: Monday, 21 March 2005
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