|Northern snakehead, Channa argus|
The snakeheads are members of the freshwater perciform fish family Channidae, native to Africa and Asia. These elongated, predatory fish are distinguished by a long dorsal fin, large mouth and shiny teeth. They breathe air with gills as well as with suprabranchial organs developing when they grow older, which is a primitive form of a labyrinth organ. The two extant genera are Channa in Asia and Parachanna in Africa, consisting of about 35 species.
They have become notorious as an invasive species.
The various species of snakeheads differ greatly in size. "Dwarf snakeheads", such as Channa gachua, grow to 25 cm (9.8 in). Most other snakeheads reach between 60 and 90 cm (24 and 35 in). Three species (Channa barca , Channa marulius and Channa micropeltes) can reach a length of more than 1 m (3 ft 3 in).
Snakeheads are thrust-feeders which consume plankton, aquatic insects, and mollusks when small. As adults, they mostly feed on other fish, such as carp, or on frogs. In rare cases, small mammals such as rats are taken.
Channidae are well represented in the fossil record and known from numerous specimens. Research indicates snakeheads likely originated in the south Himalayan region of Indian subcontinent (modern-day northern India and eastern Pakistan) at least 50 million years ago (Mya), during the Early Eocene epoch. Two of the earliest known species, Eochanna chorlakkiensis Roe 1991 and Anchichanna kuldanensis Murray & Thewissen, 2008, have both been found in the Middle Eocene of Pakistan. By 17 Mya, during the Early Miocene, Channidae had spread into western and central Eurasia, and by 8 Mya, during the late Tortonian, they could be found throughout Africa and East Asia. As Channidae are adapted to climates of high precipitation with mean temperatures of 20°C (68°F), their migrations into Europe and Asia correspond to the development of the Intertropical Convergence Zone, which increased air humidity, and the intensification of the East Asian monsoon, respectively. Both weather patterns emerged due to greater vertical growth of the Alps, Pyrenees, and Himalayas, which affected Eurasian climatic patterns.
Ecological concerns 
Snakeheads can become invasive species and cause ecological damage because they are top-level predators, meaning they have no natural enemies outside of their native environment. Not only can they breathe atmospheric air, but they can also survive on land for up to four days, provided they are wet, and are known to migrate up to 1/4 mile on wet land to other bodies of water by wriggling with their body and fins. National Geographic has referred to snakeheads as "Fishzilla" and the National Geographic Channel reports that the "northern snakehead reaches sexual maturity by age 2 or 3. Each spawning-age female can release up to 15,000 eggs at once. Snakeheads can mate as often as five times a year. This means in just two years, a single female can release up to 150,000 eggs."
Intentional introductions 
Humans have been introducing snakeheads to nonindigenous waters for over 100 years. In parts of Asia and Africa, the snakehead is considered a valuable food fish, and is produced in aquacultures (fisheries motivation) or by ignorance (as was the case in Crofton, Maryland). Some examples of the introduction of snakeheads to nonindigenous waters include:
- Channa maculata was introduced to Madagascar and to Hawaii around the end of the 19th century. It can still be found there today.
- Channa striata was introduced to islands east of the Wallace line by governmental programs in the latter half of the 20th century. In Fiji, the introduction failed.
- Channa asiatica, which is native to southern China, was introduced to Taiwan and to southern Japan; the origin and reason of the introduction is unknown.
- Channa argus, which is native to northern China (Amur River), was introduced to central Asia (Kazakhstan, Turkmenistan, Uzbekistan). It was introduced to Japan about 100 years ago due to fisheries motivations. Its introduction to Czechoslovakia by the government in the 1960s failed.
Reported sightings 
In the United States 
Snakeheads became a national news topic in the United States because of the appearance of Channa argus, commonly known as northern snakeheads, spawning in a Crofton, Maryland pond in 2002. Northern snakeheads became permanently established in the Potomac River around 2004, and possibly established in Florida. Apparently unestablished specimens have been found in Wawayanda, New York, two ponds in Philadelphia, Pennsylvania and reservoirs in North Carolina.
In what was determined by the Army Corps of Engineers to be an isolated incident, a fisherman caught a single snakehead on October 2004 while fishing from Lake Michigan at Burnham Harbor in Chicago, Illinois. According to the United States Environmental Protection Agency, snakeheads have also been spotted in California, Florida, Hawaii, Maine, Maryland, Massachusetts, and Rhode Island.
On April 25, 2011, a northern snakehead was found above Virginia's Great Falls near Whites Ferry. Great Falls was supposedly a natural barrier that the fish was unable to cross. It is apparently the first time a northern snakehead was found above the falls.
In May 2011, a Brooklyn fish importer was arrested for importing 350 live snakeheads into New York. He had tried to pass the fish off as Chinese black sleepers (Bostrychus sinensis) in an effort to mislead customs. He also admitted to importing six more shipments in 2010. It is unknown if any of the fish had been released into local waterways.
On August 16, 2011, Delaware Department of Natural Resources and Environmental Control fisheries biologists captured a 25-inch snakehead in Beck's Pond, which they asserted had been illegally introduced. Officials warned that the snakeheads are known for aggressively protecting their young, and people should not try to catch the smaller fish.
On March 28, 2012, Don Cosden, from Maryland state's Department of Natural Resources confirmed that they were offering prizes for catching and killing any snakehead fish. To enter the contest, anglers had to catch, kill and then post a picture of themselves with a dead snakehead caught in Maryland on the DNR's Web site.
As food 
Snakeheads are considered valuable food fish. Called nga gyi in Burmese, it is a prized fish eaten in a variety of ways. In Vietnam, they are called ca loc, ca qua, or ca chuoi, it is prized in clay pot dishes and pickled preparations. Larger species, such as Channa striata, Channa maculata, and Parachanna obscura, are farmed in aquaculture. In the United States, chefs have suggested controlling the snakehead invasion by serving them in restaurants.
In popular culture 
In CSI: NY, snakeheads are placed in mezcal bottles which are found by the team at the crime scenes in Season 7 Episode 4 ("Sangre Por Sangre").
In The Penguins of Madagascar episode "Snakehead!", a northern snakehead (wrongly identified by Kowalski as "the snakehead trout") invades a pond in Central Park and threatens to devour anything in its path. A mother duck and her ducklings seek the aid of the penguins from the Central Park Zoo (Skipper, Kowalski, Rico, and Private) to assess the situation. The penguins build a submarine to scour the pond, where they find the snakehead and destroy it by throwing a bottle of heavily-shaken-up soda down its throat (in a parody of Jaws), turning it into a large supply of sushi when the bottle explodes.
In the Animal Planet TV series River Monsters, Jeremy Wade shows a dramatization of a snakehead, "the fish from hell", stalking an unsuspecting baby and Chihuahua. With the help of a snakehead researcher, however, Wade shows that although it is capable of living outside of water and is able move on land, its weak pectoral muscles make movement difficult and render the snakehead an unlikely "stalker" on land.
In the "Soprano Home Movies" episode of the HBO series The Sopranos, Bobby and Tony discuss snakeheads being found in the Adirondack area of New York when visiting Bobby's cottage. The fish had originally been mistaken as bowfins.
The snakeheads comprise two extant genera:
- Channa (33 species native to Asia)
- Parachanna (four African species, including one only known from fossil remains)
Two other genera are only known from fossils:
See also 
- Murray, A. M. & Thewissen, J. G. M. (2008): Eocene actinopterygian fishes from Pakistan, with the description of a new genus and species of channid (channiformes). Journal of Vertebrate Paleontology, 28 (1): 41-52
- Pinter, H. (1986). Labyrinth Fish. Barron's Educational Series, Inc., ISBN 0-8120-5635-3.
- Roe, L. J. (1991): Phylogenetic and Ecological Significance of Channidae (Osteichthyes Teleostei) from the Early Eocene Kuldana Formation of Kohat, Pakistan. Contributions From The Museum Of Paleontology, The University Of Michigan, VOL. 28, NO. 5, PP. 93-10
- Böhme, Madelaine (May 2004). "Migration history of air-breathing fishes reveals Neogene atmospheric circulation patterns". Geology 32 (5): 393–396. doi:10.1130/G20316.1. Retrieved 2008-07-09.
- Cruz, Elena (2007-12-03). "Snakehead Frenzy!". NGC Blog. National Geographic Channel.
- Courtenay, Jr., Walter R. and James D. Williams. USGS Circular 1251: Snakeheads (Pisces, Chinnidae) - A Biological Synopsis and Risk Assessment. U.S. Department of the Interior, U.S. Geological Survey. 2004-04-01. Retrieved 2012-04-16.
- Potomac snakeheads not related to others Associated Press, Baltimore Sun, 27 April 2007.
- Yakin, Heather (August 6, 2008). "DEC sprays poison to kill snakeheads". The Times Herald Record.
- Canadian Press (October 17, 2004). "Great Lakes biologists worry about 'frankenfish'". CTV.ca. Retrieved April 29, 2011.
- "Chicago Angler nets Snakehead in Lake Michigan". Great Lakes Sport Fishing Council. October 18, 2004. Retrieved April 29, 2011.
- "Snakehead Fish Found In Lake Michigan". Life. Retrieved April 29, 2011.
- "History of introduction in the United States: Four species of snakeheads (Channa argus, C. marulius, C. micropeltes, and C. striata) have been recorded from open waters of the United States (California, Florida, Hawaii, Maine, Maryland, Massachusetts, and Rhode Island), and two have become established as reproducing populations." Injurious Wildlife Species; Snakeheads Environmental Protection Agency. Retrieved 17 February 2008.
- "Snakehead caught near White's Ferry". Fairfax Times. April 29, 2011. Retrieved May 10, 2011.
- Thomas Zambito (April 28, 2011). "Fish importer busted trying to smuggle fish-chomping 'fishzilla' snakeheads into New York". New York Daily News. Retrieved April 29, 2011.
- Clarke, Matt (April 2008). "Snakehead catch 'a hoax'". Practical Fishkeeping.
- Carletti, Fabiola; Gillis, Wendy (2010-08-09). "Welland Canal safe from ‘Frankenfish'". The Star (Toronto).
- B.C.'s snakehead caught after Burnaby pond drained. CBC News (Posted: June 8, 2012)
- Froese, Rainer, and Daniel Pauly, eds. (2006). "Channidae" in FishBase. January 2006 version.
- "Channidae". Integrated Taxonomic Information System. Retrieved 20 March 2006.
|Wikimedia Commons has media related to: Channa striata|
|Wikispecies has information related to: Channidae|
- Snakeheads—A Biological Synopsis and Risk Assessment published by the U.S. Geological Survey
- About.com's article on Snakeheads
- snakeheads.org world's largest website for snakeheads
- Overview of Northern Snakehead biology
- Fish or Foul: Snakeheads near Washington, D.C., and the people who love them