Chesapeake Bay Introduced Species Database

Channa argus

Common name(s):
Northern Snakehead
The Northern Snakehead, native to Asia, was first caught in a pond in Crofton, MD in 2002. They are a major concern here because they are voracious predators and could impact our native fish species. Their 2002 discovery prompted a rapid response and eradication effort that lead to the removal of over 1,000 juvenile fish. However, in 2004, an established population of Snakeheads was found in the Potomac River. Genetic analysis indicates that the fish have been introduced many times in North America. Because Snakeheads are imported for food and occasionally sold in the aquarium trade, their introductions are likely to be a combination of accidental and intentional (illegal) introductions. Snakeheads have not yet had a significant ecological or economic impact, but the Potomac River population has spread to brackish waters near the mouth of the river and may be moving into other tributaries. In April-July of 2011, several catches of snakeheads were reported in the Bay outside the Potomac River, including St. Jeromes Creek, Nanticoke River, and up the bay to the Rhode and Northeast Rivers. Their spread may have resulted from heavy winter and early spring rains which resulted in unusually low salinities in Chesapeake Bay permitting wider dispersal.
Image courtesy of Virginia Department of Natural Resources.

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Environmental Tolerances

For Survival
For Reproduction
Temperature (ºC)
0 35 null null
Salinity (‰)
0 15 0 null
null null    
Salinity Range

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Age and Growth

Minimum Adult Size (mm)
300 300
Typical Adult Size (mm)
null null
Maximum Adult Size (mm)
850 850
Typical Longevity (yrs)
null null
Maximum Longevity (yrs)
null null

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Reproductive Season
May June July
Typical Number of Young
per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual Reproduction
Fertilization Type(s)
More than One Reproductive
Event per Year
Reproductive Strategy
Egg/Seed Form

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Minimum Typical Maximum
Egg/Seed Development Time (days)
1.2 1.5 5
Larval/Seed Development Period (days)
null null null
Male Maturation Age (yrs)
2 2.5  
Female Maturation Age (yrs)
2 2.5  
Larval/Seed Form  
lecithotrophic; planktotrophic

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Locomotion and Abundance in Chesapeake

demersal unknown
nektonic unknown
nektonic unknown

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Habitat Preferences

Primary Horizontal Habitats
nontidal freshwater; fresh (non-tidal) marsh; swamp;tidal fresh marsh; grass bed nontidal freshwater; fresh (non-tidal) marsh; swamp;tidal fresh marsh; grass bed nontidal freshwater; fresh (non-tidal) marsh; swamp; tidal fresh marsh; grass bed
Secondary Horizontal Habitats
null unstructured unstructured
Reproductive Horizontal Habitats
n/a n/a nontidal freshwater; fresh (non-tidal) marsh; swamp; tidal fresh marsh; grass bed
Vertical Habitats
demersal, planktonic epibenthic, nektonic epibenthic, nektonic
Substrate Type
vegetation silt; mud; vegetation silt; mud; vegetation
Tidal Height Location
subtidal subtidal subtidal
Wave Exposure
low; protected
Water Flow
stagnant; slow

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Trophic Interactions

Trophic Status
non-feeding; planktotrophic carnivore carnivore
Common Food/Prey Items
zooplankton small crustaceans, fish larvae fishes, frogs, crustaceans, aquatic insects
Common Competitors
null Micropterus salmoides Micropterus salmoides
Common Consumers
null null Humans

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Life History: Environmental Tolerances: Salinity- In experiments,C. argus survived a gradual salinity (1 ppt/day) to 15-18 ppt, and long-term (30+) day exposure to 10 ppt at 15-20 C, but began to die after 10-12 days at 10 ppt and 25 C (Northern Snakehead Working Group 2007). Oxygen- Adult and juvenile C. argus are air-breathers, capable of supporting most of their oxygen requirements by using suprabranchial chambers to absorb inhaled oxygen (Courtenay and Williams 2004).

Reproduction: Reproductive Season- Dates are for one group of lakes in the Syr-Dar'ya Basin, Russia (May-June), and one observation in China (Courtenay and Williams 2004). Other populations spawn 3-5 times per year and may have more prolonged seasons (Courtenay and Williams 2004). Typical Number of Young per Reproductive Event- Reported fecundities range from 22,000 to 115,000 eggs per female. Individual spawnings range from 1,000 to 15,000 (Courtenay and Williams 2004).

Development: Egg/Seed Development Time (days)- Development times range from 1.2 days at 31 C to 5 days at 18 C (Courtenay and Williams 2004). Maturation Age (yrs)- Reported maturation ages are 2 years in Japan and 2-3 years in the Amur Dar'ya and Syr Dar'ya basins (Courtenay and Williams 2004).

Age and Growth: Reported maturation sizes are 30 cm in Japan and 30-35 years in the Amur Dar'ya and Syr Dar'ya basins (Courtenay and Williams 2004).

Locomotion and Abundance in Chesapeake: Larval, Juvenile Locomotion- Eggs and larvae are guarded by both adults in a nest made of pieces of aquatic vegetation. Larvae remain in the nest until the yolk is absorbed, after which they begin to swim and feed on plankton (Courtenay and Williams 2004).
Community Ecology: Habitat Preferences: Primary Horizontal Habitats- 'Stagnant shallow ponds or swamps with mud substrate and aquatic vegetation; slow muddy streams' (Okada 1960). Also occurs in canals, reservoirs, lakes, and rivers (Dukravets and Machulin, 1978; Dukravets 1992; Nina Bogutskaya, personal commun., 2002). This species is an obligate airbreather (Uchida, 1933). It appears to occupy waters, usually with vegetation, close to shore, and also feeds in schools (Nina Bogutskaya, personal commun., 2002).' Courtenay and Williams 2004] During the snakehead furor of 2002, C. argus was widely publicized as a 'walking fish', but its terrestrial capabilities appear to be limited to burrowing in the mud of drying ponds and, possibly, brief wriggles over wet ground. Other species of Channa, with ventrally flattened bodies, are more capable of overland movement (Courtenay and Williams 2004; Dolin 2002)

This data was last modified on Thursday, May 23rd, 2013.
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