Northern snakehead (Channa argus)

Synonyms: Ophicephalus argus, Ophiocephalus argus, Channa argus warpachowskii

Common Names: Snakehead, Amur snakehead, eastern snakehead, frankenfish

Description:

Northern snakehead (Channa argus) is a long, predatory freshwater fish from temperate East Asia that can breathe air and even move short distances over land [1]. It was released into U.S. waters from live-food markets and aquariums and has built breeding populations in several states, including Michigan [1]. MISIN tracks it because it is a top predator that eats and competes with native fish, it spreads easily, and it can survive conditions that kill most other fish [1][2].

Identification:

Northern snakehead is a long, thin fish that can grow up to about 3 feet long [1]. It is tan to brown with large, dark blotches scattered along its sides and back, and it has a flattened, snake-like head with a big, toothy mouth ? the look that gives it its name [1][2]. The clearest shape clue is its fins: a single long dorsal fin runs most of the length of its back, and its anal fin underneath is also long and about the same size [1]. Its pelvic fins sit far forward, right behind the front (pectoral) fins, and a dark stripe runs from the eye to the edge of the gill cover [1][2].

It is present in invaded waters year-round and even survives under ice, because it gulps air at the surface and can live in low-oxygen water [1]. Anglers most often encounter it in summer in shallow, weedy, slow water; out of water, it can stay alive for several days if kept moist, so never assume a stranded one is dead [1].

At-a-glance cues:

1. Long, thin fish, up to about 3 feet, tan to brown with large dark blotches [1][2]
2. Flattened, snake-like head with a large, toothy mouth [1][2]
3. A single long dorsal fin running most of the back, with a long anal fin of similar size [1]
4. Pelvic fins set far forward, directly behind the front fins [1]

Habitat:

Northern snakehead lives in slow or still fresh water ? ponds, lakes, marshes, slow rivers, canals, and ditches ? and favors shallow, weedy areas [1]. It is extremely hardy: it breathes air with a lung-like organ, so it survives in warm, stagnant, low-oxygen water that would kill most fish, and it tolerates cold, even surviving under winter ice [1].

The fish is native to temperate East Asia ? China, the Russian Far East, and Korea [1]. It is not native to North America. It first established in the United States in 2002 at a pond in Maryland and now has breeding populations in several states, including along the Potomac River and in Michigan [1]. As a predator, its "hosts" are really its prey ? mostly other fish, plus crayfish, frogs, and occasionally birds and small mammals [1].

Reproduction:

Northern snakehead reaches new water almost entirely through people. It was sold live in food markets and as an aquarium fish, and it spreads when people release or dump it, or move it as live food [1]. It can also travel short distances overland ? young fish can survive out of water for up to several days and wriggle to a nearby pond ? and it spreads on its own through connected waterways [1]. So it can arrive as a released pet, a dumped market fish, or by moving in from connected water.

It breeds fast and guards its young, which makes it hard to control. A female can release roughly 1,300 to 1,500 eggs at a time and may spawn several times a year, and both parents build a floating nest and protect the eggs and young [1]. The fish can mature in as little as one to three years [1]. Because of this, a few released fish can build a population quickly, so the keys to stopping it are never releasing it and catching new populations early [1].

Impact and Damage:

Northern snakehead is not dangerous to people ? it is eaten as food in much of its native range ? though it has sharp teeth, so handle it with care. The real damage is to fisheries and aquatic ecosystems. As a voracious top predator, it eats large numbers of native fish (adults feed almost entirely on other fish), along with crayfish and frogs, and it competes with native predators such as largemouth bass for the same food [1].

Because it is so hardy, breeds quickly, and guards its young, it can build dense populations and reshape the food web of a pond, lake, or river, putting pressure on native fish [1]. Once it is established in a waterway, it is very difficult and costly to remove, which is why agencies treat any new sighting as a high-priority threat [1].

Similar species:

Blotched snakehead (Channa maculata) is another snakehead species with the same long dorsal and anal fins and forward-set pelvic fins, but its pattern is more of bold dark bars preceded by pale bars rather than scattered blotches [1].

North American bowfin (Amia calva) is the native fish most often mistaken for a snakehead, since both are long with a long dorsal fin. But bowfin is olive with a net-like (mottled) pattern, often with bright green lower fins and a rounded tail, and its anal fin is short ? unlike the snakehead's long anal fin and forward pelvic fins [1]. Burbot (Lota lota) is a native fish with a long, eel-like, mottled body, but it has a single whisker (barbel) under its chin and two dorsal fins (a short one followed by a long one), which snakeheads lack [1].

Monitoring and rapid response:

Signs to watch for:

1. A long, blotchy brown fish with a flattened, snake-like, toothy head [1][2]
2. A single long dorsal fin running most of the back and a long anal fin of similar size [1]
3. One caught while fishing, or seen in a pond, market tank, or aquarium [1]

What you can do:

1. Never buy, keep, transport, or release a live northern snakehead ? importing it or moving it across state lines is illegal under federal law [1][3].
2. Never dump aquarium fish or bait, or release live food-market fish, into the wild.
3. If you catch one, do not throw it back or move it alive ? it can survive out of water, so kill it (do not assume a stranded fish is dead), keep it on ice, take clear photos, note the exact location, and report it right away (below) [2].
4. Clean, drain, and dry boats, livewells, and bait buckets when moving between waters [1].
5. Natural area crews and agencies respond to new populations with rapid action ? netting, electrofishing, and sometimes draining or targeted treatment ? along with monitoring [1].

When to call a professional:

1. Any confirmed or suspected northern snakehead ? removing or responding to it is a job for your fisheries or natural resources agency.
2. Any water where one has been caught more than once, which may signal a breeding population.
3. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. U.S. Geological Survey, Nonindigenous Aquatic Species Database. Channa argus (Northern Snakehead) ? Species Profile (summarizes Saylor et al. 2012 and others). nas.er.usgs.gov
2. Michigan Department of Natural Resources. Invasive Species: Northern Snakehead (Channa argus). michigan.gov/invasives
3. U.S. Fish & Wildlife Service. Snakehead (Channa argus). fws.gov

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