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Northern Snakehead - Channa argus

Aquatic Invasive Species
Non-native Species
Not Documented

Global Rank: G5
State Rank: SNA
(see State Rank Reason below)

Agency Status


External Links

State Rank Reason (see State Rank above)
A conservation status rank is not applicable because this species is not a suitable target for conservation activities as a result of being exotic or introduced. This species is currently not known to occur in the state of Montana.
General Description
The Northern Snakehead (NOSN) is a long, slender fish with a single dorsal fin running the length of the fish (Fuller et al. 2018 ). Maximum size exceeds 85 cm (33 inches)(Fuller et al. 2018 ). The Overall color of this species is brown with dark blotches (Fuller et al. 2018 ). It has a somewhat flattened head with eyes that are located in a dorsolateral position on the anterior part of the head; anterior nostrils are present and tubular; dorsal and anal fins are elongated, and all fins are supported only by rays (Courtenay and Williams 2004). Males are darker in color, and have a broader head, as compared to females (Gascho Landis and Lapointe 2010). Juveniles have a similar color and pattern as the adults. NOSN are morphologically similar to the North American native Bowfin (Amia calva), and the two are often misidentified (Fuller et al. 2018 ). Snakeheads can be distinguished from Bowfin by the position of pelvic fins (directly behind pectoral fins in snakeheads, farther back on body in Bowfin. It could also be mistaken for the MT native fish, the burbot (Lota lota).

Diagnostic Characteristics
Snakeheads can be distinguished from Bowfin by the position of pelvic fins (directly behind pectoral fins in snakeheads, farther back on body in Bowfin) and the size of the anal fin (elongate and similar in size to dorsal fin in snakeheads, short and much smaller than dorsal fin in Bowfin) (Fuller et al. 2018 ). Additionally, Bowfin can be identified by the presence of a bony plate between the lower jaws (gular plate) and a distinctive method of swimming through undulation of the dorsal fin (Fuller et al. 2018 ). NOSN is also very similar to the Burbot (Lota lota), another North American native fish species (Fuller et al. 2018 ), but does not have a single barbel on its chin.

Range Comments
Native Range
Northern Snakehead is native to China, Russia and Korea (Courtenay and Williams 2004). It is native to all but the northeastern regions of Korea, as well as the rivers of China, southward and southwestward to the upper tributaries of the Yangtze River basin in northeastern Yunnan Province (Courtenay and Williams 2004).

Global Range
NOSN are established in Virginia, Maryland, Pennsylvania, New York, and Arkansas, but are not established in South California, Florida, Illinois, Massachusetts, Delaware, and North Carolina where a few individual fish have been collected (Fuller et al. 2018 ). However, the NOSN was eradicated from the Crofton pond in Maryland where it was established (Fuller et al. 2018 ). The species is well established in the Potomac River and several of its tributaries in Virginia and Maryland (Starnes et al. 2011). Officials believe NOSN may have gotten into the lower Schuylkill River and Delaware River in Pennsylvania and see no practical means to eradicate them (Fuller et al. 2018 ). In March 2009, the population in Little Piney Creek drainage received an eradication attempt with the application of rotenone to more 700 km of creeks, ditches, and backwaters. However, more snakeheads have been found since this effort (Fuller et al. 2018 ). The population in Catlin Creek, New York was also treated with rotenone. According to the Northern Snakehead Working Group (NSWG) of the U.S. Fish and Wildlife Service, NOSN likely arrived in U.S. waters by importation for the live food fish market (NSWG 2006). Unauthorized intentional release from this trade, as was the case in the founding individuals of the Crofton pond population in Maryland, continues to be the major mechanism for introduction (Courtenay and Williams 2004; Fuller et al. 2018 ). In Canada, Herberg et al. (2007) identified two watersheds in the Toronto area along Lake Ontario; the Rideau River watershed and Cedar Creek watershed (between Lake Erie and Lake St. Clair) posed additional vectors for introduction.

Montana Range
This species is not currently known to occur in any waterbodies of the state of Montana or adjacent states.

For maps and other distributional information on non-native species see:
Nonindigenous Aquatic Species Database from the U.S. Geological Survey
Invasive Species Habitat Tool (INHABIT) from the U.S. Geological Survey
Invasive Species Compendium from the Centre for Agriculture and Bioscience International (CABI)
EDDMapS Species Information EDDMapS Species Information

Although Northern snakeheads can survive up to four days out of the water, overland migration is only possible for juveniles (Courtenay and Williams 2004). The rounded body of the adult northern snakehead is not as conducive to overland migration as observed in more horizontally flattened snakehead species (Fuller et al. 2018 ).

This species prefers to live in stagnant, shallow (<2 m) ponds or swamps with mud substrate or aquatic vegetation and slow muddy streams, it also occurs in canals, reservoirs, lakes, and rivers (Courtenay and Williams 2004).

Food Habits
Adult snakeheads feed almost exclusively on other fishes (>97% of diet), with the remainder of their diet composed of crustaceans, frogs, small reptiles, and sometimes small birds and mammals (Courtenay and Williams 2004; Saylor et al 2012). Northern snakehead fry initially feed on zooplankton, before moving on to a diet of small insects and crustaceans (e.g., cladocerans, copepods, small chironimid larvae) (Fuller et al. 2018 ). Juveniles may feed on small fish, including goldfish (Carassius spp.) and roach (Rutilis spp.; Courtenay and Williams 2004). As an adult, the NOSN is a voracious feeder (Okada 1960), and its diet may include fish up to 33 percent of its body length (Courtenay and Williams 2004). Adult prey items have included: loach, sunfish, carp, perch, zander, grass carp, catfishes, crayfish, dragonfly larvae, beetles, and frogs (Fuller et al. 2018 ). These predatory fishes may compete with native species for food and habitat (Fuller et al. 2018 ). Juveniles eat zooplankton, insect larvae, small crustaceans, and the fry of other fish (Fuller et al. 2018 ).

Northern snakeheads are obligate air-breathers, capable of survival in poorly oxygenated waters (Fuller et al. 2018 ). Although this species prefers to live in stagnant shallow (< 2 m) ponds or swamps with mud substrate or aquatic vegetation and slow muddy streams, it also occurs in canals, reservoirs, lakes, and rivers (Courtenay and Williams 2004). This species does show some seasonal changes microhabitat selection and preference, utilizing deeper water in winter months and shallow areas with macrophytes during the spawning season (Lapointe et al. 2010). It can adapt to a wide range of aquatic environments, as evidenced by the spread of reproducing, introduced populations throughout Asia and Japan (Fuller et al. 2018 ). While its optimum maximum air temperature range is 5-16°C (Herborg et al. 2007), the northern snakehead has a wider latitudinal range and temperature tolerance (0 to >30°C, including frost days) than other snakehead species (Dukravets and Machulin 1978, in Courtenay and Williams 2004; Okada 1960). Reduced metabolism and oxygen demand at low temperatures allows this species to survive extended periods of ice cover (Frank 1970, in Courtenay and Williams 2004). Upper salinity tolerances have been experimentally determined to be between 15 and 18 ppt (at temperatures of 15-24°C; NSWG 2006).

Reproductive Characteristics
In its native range, NOSN reproductive maturity is typically reached when fish are 2-3 years old (Dukravets and Machulin 1978), but may occur only after one year of growth in some introduced populations (USACE 2011). In the U.S., NOSN spawning has been observed to start by the end of April, peak in June, and continue through August (Gascho Landis et al. 2011). Adult females build circular floating nests from clipped aquatic plants and release their pelagic, nonadhesive, buoyant eggs on top (Gascho Landis and Lapointe 2010). Each spawn can consist of 1300-1500 bright orange-yellow eggs (about 1.8 mm diameter), with up to five spawns occurring within a year. NOSN fecundity can range from 22,000-51,000 in its native range (Amur River basin; Nikol'skiy 1956) to 28,600-115,000 in an introduced population (Syr Dar'ya basin, Turkmenistan/Uzbekistan; Dukravets and Machulin 1978). Both parents guard the nest of eggs from predation and continue to guard the hatched fry for several additional weeks (Courtenay and Williams 2004, Gascho Landis and Lapointe 2010). Depending on water temperature, eggs may hatch in fewer than three days (28 hours at 31°C, 45 hours at 25°C, and 120 hours at 18°C; Gascho Landis and Lapointe 2010). Larvae experience rapid growth after their first two weeks, though overall individual growth rate in North American populations appears to be less than that in both native and introduced Asian populations (Gascho Landis et al. 2011).


Threats or Limiting Factors
While its optimum maximum air temperature range is 5-16°C (Herborg et al. 2007), the northern snakehead has a wider latitudinal range and temperature tolerance (0 to > 30°C, including frost days) than other snakehead species. Reduced metabolism and oxygen demand at low temperatures allows this species to survive extended periods of ice cover. The NOSN has become widely popular in ethnic markets and restaurants over the last two decades, such that this species comprised the greatest volume and weight of all live snakehead species imported into the U.S. until 2001 (Courtenay and Williams 2004, NSWG 2006). Snakehead's resilient nature reportedly makes them more desirable than carps for ceremonial release, and some interest in recreational fishing may also exist (Mendoza-Alfaro et al. 2009, NSWG 2006).

Due to this species' temperature tolerance range, it would likely survive in a host of waterbodies in Montana if introduced to the state; therefore, keeping this species out of the state is the best preventative measure from it becoming another invasive species in the state.

  • Literature Cited AboveLegend:   View Online Publication
    • Courtenay, W. R., Jr., and J. D. Williams. 2004. Snakeheads (Pisces: Channidae) -- A biological synopsis and risk assessment. U.S. Department of the Interior, U.S. Geological Survey Circular 1251, 143 p.
    • Dukravets, G.M., and Machulin, A.I., 1978, The morphology and ecology of the Amur snakehead, Ophiocephalus argus warpachowskii, acclimatized in the Syr Dar'ya basin. Journal of Ichthyology, v. 18, no. 2, p. 203-208.
    • Frank, S. 1970. Acclimitization experiments with Amur Snakehead (Ophiocephalus argus warparchowskii) (Berg 1909) in Czechoslovakia. Vstenik eskoslovenski Spelenosti Zoologicke. v. 34, pp. 277-283.
    • Fuller, P.L., Benson, A.J., Nunez, G., Fusaro, A., and Neilson, M., 2018, Channa argus (Cantor, 1842): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL,, Revision Date: 7/24/2018, Peer Review Date: 4/1/2016, Access Date: 8/13/2018
    • Gascho Landis, A.M., and N.W.R. Lapointe. 2010. First record of a northern snakehead (Channa argus Cantor) nest in North America. Northeastern Naturalist 17(2): 325- 332.
    • Gascho Landis, A.M., N.W.R. Lapointe, and P.L. Angermeier. 2011. Individual growth and reproductive behavior in a newly established population of northern snakehead (Channa argus), Potomac River, USA. Hydrobiologia 661:123-131.
    • Herborg L. M., N. E. Mandrak, B. C. Cudmore, and H. J. MacIsaac. 2007. Comparative distribution and invasion risk of snakehead (Channidae) and Asian carp (Cyprinidae) species in North America. Canadian Journal of Fisheries and Aquatic Sciences. 64:1723-1735.
    • Lapointe, N.W.R., J.T. Thorson, and P.L. Angermeier. 2010. Seasonal meso- and microhabitat selection by the northern snakehead (Channa argus) in the Potomac River system. Ecology of Freshwater Fish 19:566-577.
    • Mendoza-Alfaro, R., S. Contreras, P. Koleff, C. Ramirez, C. Escalera, P. Alvarez, B. Cudmore, N. Mandrak, J. P. Fisher, R. Orr, W. Courtenay, G. Greene, and D. Lee. 2009. Proposed trinational risk assessment guidelines for invasive alien species: test cases for the snakeheads (Channidae) and armored catfishes (Loricariidae) in North American waters. Commission for Environmental Cooperation
    • Northern Snakehead Working Group (NSWG). 2006. National control and management plan for the northern snakehead (Channa argus). Department of the Interior, unpublished manuscript.
    • Okada, Y. 1960. Studies of the freshwater fishes of Japan, II, Special part. Journal of the Faculty of Fisheries Prefectural University of Mie 4: 31-860.
    • Saylor, R.K., N.W.R. Lapointe, and P.L. Angermeier. 2012. Diet of non-native northern snakehead (Channa argus) compared to three co-occurring predators in the lower Potomac River, USA. Ecology of Freshwater Fish 21:443-452.
    • Starnes, W.C., J. Odenkirk, and M.J. Ashton. 2011. Update and analysis of fish occurrences in the lower Potomac River drainage in the vicinity of Plummers Island, Maryland— Contribution XXXI to the natural history of Plummers Island, Maryland. Proceedings of the Biological Society of Washington 124(4):280-309.
    • U.S. Army Corps of Engineers (USACE). 2011. Northern snakehead. Available Accessed: 13 September 2018
  • Additional ReferencesLegend:   View Online Publication
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    • Joslin, Gayle, and Heidi B. Youmans. 1999. Effects of recreation on Rocky Mountain wildlife: a review for Montana. [Montana]: Montana Chapter of the Wildlife Society.
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Northern Snakehead — Channa argus.  Montana Field Guide.  .  Retrieved on , from