Channidae

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Snakehead

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Channidae

Genera

Channa
Parachanna

Channidae is a family of freshwater perciform fish commonly known as snakeheads, and is native to Africa and Asia. There are two genera, Channa in Asia, and Parachanna in Africa, consisting of 30 species. These predatory fishes are distinguished by a long dorsal fin, small head with large head scales on top, large mouth and teeth. They have a physiological necessity of breathing atmospheric air, which they do with a suprabranchial organ: a primitive form of a labyrinth organ.

They are considered a valuable food fish. Larger species like Channa striata, Channa maculata or Parachanna obscura are farmed in aquaculture. Snakeheads feed on plankton, aquatic insects, and mollusks when small. When adult, they mostly feed on other fish like carp, or frogs. In rare cases, small mammals such as rats are taken. The size of the snakehead species differs greatly. "Dwarf snakeheads" like Channa gachua grow to 10 inches (25 cm). Most snakeheads grow up to 2 or 3 ft. (60–100 cm). Only two species (Channa marulius and Channa micropeltes) can reach a length of more than 1 meter and a weight of more than 6 kg.

Snakeheads are also sold as pets, and also locally known as "toman" in the Malay language.

1 Species
2 Ecological concerns
- 2.1 Sightings in the U.S.
- 2.2 Removal
3 References
4 External links

[edit] Species

There are 31 species in two genera:

Genus Channa
- Borna snakehead, Channa amphibeus (McClelland, 1845).
- Northern snakehead, Channa argus (Cantor, 1842).
- Channa asiatica (Linnaeus, 1758).
- Channa aurantimaculata Musikasinthorn, 2000.
- Channa bankanensis (Bleeker, 1852).
- Barca snakehead, Channa barca (Hamilton, 1822).
- Rainbow snakehead, Channa bleheri Vierke, 1991.
- Channa burmanica Chaudhuri, 1916.
- Channa cyanospilos (Bleeker, 1853).
- Channa gachua (Hamilton, 1822).
- Channa harcourtbutleri (Annandale, 1918).
- Forest snakehead, Channa lucius (Cuvier, 1831).
- Channa maculata (Lacépède, 1801).
- Channa marulioides (Bleeker, 1851).
- Great snakehead, Channa marulius (Hamilton, 1822).
- Channa melanoptera (Bleeker, 1855).
- Black snakehead, Channa melasoma (Bleeker, 1851).
- Giant snakehead, Channa micropeltes (Cuvier, 1831).
- Channa nox Zhang, Musikasinthorn & Watanabe, 2002.
- Walking snakehead, Channa orientalis Bloch & Schneider, 1801.
- Channa panaw Musikasinthorn, 1998.
- Channa pleurophthalmus (Bleeker, 1851).
- Spotted snakehead, Channa punctata (Bloch, 1793).
- Assamese snakehead, Channa stewartii (Playfair, 1867).
- Snakehead murrel, Channa striata (Bloch, 1793).
Genus Parachanna
- Parachanna africana (Steindachner, 1879).
- Parachanna insignis (Sauvage, 1884).
- Obscure snakehead, Parachanna obscura (Günther, 1861).

[edit] Ecological concerns

Snakeheads can become invasive species and cause ecological damage because they are top-level predators, meaning that they have no natural enemies outside of their native environment. They can not only breath atmospheric air, but survive on land for up to 3 days, provided they are wet, and are known to migrate on wet land to other bodies of water using their fins.

Snakeheads became infamous in the US because of their appearance in a pond in Crofton, Maryland, in the summer of 2002. They are prohibited in several other countries like Australia because their introduction to new ecosystems may displace indigenous species. Humans have been introducing snakeheads to non-indigenous waters for over 100 years. In parts of Asia and Africa, the snakehead is considered a valuable food fish and is produced in aquacultures. Due to this fact it was introduced either on purpose (fisheries motivation) or by ignorance (as was the case in Crofton).

Some examples of the introduction of snakeheads to non-indigeneous 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 later 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. In this case the origin and reason of the introduction is unknown, but most probably due to human intervention.
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 due to cold winters.

A comprehensive work on the dangers of the introduction of snakeheads to non-indigeneous waters is that of Prof. W. Courtenay.

[edit] Sightings in the U.S.

On October 9, 2004 a fisherman caught one in Lake Michigan at Burnham Harbor in Chicago, Illinois. In July 2005 a snakehead was spotted in the waters of Flushing Meadows Park in Queens, New York City. They have also been spotted in Washington, California, Texas, Alabama, Florida, North Carolina, Virginia, Rhode Island, Maine, Massachusetts, Maryland and Pennsylvania.

One of the largest known populations of snakehead in the United States are located in the Potomac River in Maryland. Many fisherman have caught these ecosystem damaging animals.

[edit] Removal

Snakeheads may be exterminated by applying the herbicides diquat dibromide and glyphosate (tradenames such as Roundup, Rodeo) to ponds to eliminate aquatic vegetation. These death of plants cause oxygen levels to drop, and a subsequent fish kill occurs.

Approximately one to two weeks after the application of the herbicides, application of the piscicide Rotenone kills any remaining fish. Dead fish should be removed daily; however, unpleasant odors from decaying organic material are to be expected.