Channidae

Taxobox
name = Snakehead


image_width = 250px
image_caption = Northern snakehead, "Channa argus"
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Perciformes
subordo=Channoidei
familia = Channidae
subdivision_ranks = Genera
subdivision = "Channa" "Eochanna" "Parachanna"

Channidae is a family of freshwater fish commonly known as snakeheads, and is native to Africa and Asia. There are two extant genera, "Channa" in Asia, and "Parachanna" in Africa, consisting of 30-35 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 need to breathe atmospheric air, which they do with a suprabranchial organ: a primitive form of a labyrinth organ.

They are considered 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.

It is illegal to keep snakeheads as pets in thirteen states of the USA and other countries as they have become an invasive species due to irresponsible owners releasing them into the wild when they could/would no longer take care of them. If in an enclosed area they will try anything to escape. If in an aquarium they will charge at full force and tend to knock over the aquarium or shatter the glass.Fact|date=March 2008Channidae is also known as the the Northern Snakehead, or Channa Argus, and is native to Asia. There are 29 known Snakehead varieties.Fact|date=July 2008

The National Geographic Channel reported:cite web |url=http://channel.nationalgeographic.com/series/wild/3449/Overview#tab-Videos/03181_10 |title=Fishzilla: Snakehead Invasion |work=Wild |publisher=National Geographic Channel Video clip titled: "The Northern Snakehead fish wreaks havoc".] quote
A 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...

'They can travel across land and live out of water for up to three days,' [says U.S. Secretary of the Interior Gale Norton] .

[Snakeheads can breathe air unlike other fish as they] use a primitive lung above their gills... [or] 'air chambers'.

Out of the water Snakeheads rhythmically move their fins and muscular bodies back and forth: the fish equivalent of walking... It's a resourceful adaptation. [In their native Asia they must survive both wet and dry weather cycles like monsoons and droughts.]

When the Snakehead eats it is a thrust predator. It will eat its prey all at once, striking and ingesting it whole.Fact|date=July 2008

The Giant Snakehead, or Channa micropeltes, is native throughout Asia, and is the most aggressive Snakehead. They can grow to over 1.5 metres long. Adult Snakeheads force their hatchlings to breathe air by pushing them to the surface.

From 2002 to 2003, one Los Angeles supermarket was found to have sold approximately 25,000 dollars worth of illegal live Snakeheads which caused breakouts in local eco systems.

It has had recent sightings in Lincolnshire (UK) (which proved to be hoax) and in the U.S. National Geographic referred to it as "Fishzilla".cite web |url=http://natgeowild.co.uk/explore/Fishzilla/ |title=Fishzilla |work=Nat Geo Wild |publisher=NGC-UK Partnership] cite web |url=http://ngcblog.nationalgeographic.com/ngcblog/2007/12/snakehead_frenzy.html |title=Snakehead Frenzy! |work=NGC Blog |publisher=National Geographic Channel |date=2007-12-03 |first=Elena |last=Cruz]

pecies

[
Courtenay, Jr., Walter R. and James D. Williams. [http://fisc.er.usgs.gov/Snakehead_circ_1251/html/index.html 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 2007-07-16.] ] There are about 30-35 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 ornatipinnis" Britz, 2007.cite journal | journal = Ichthyological Exploration of Freshwaters | volume = 18 | issue = 4 | year = 2007 | pages = 335–344 | title = "Channa ornatipinnis" and "C. pulchra", two new species of dwarf snakeheads from Myanmar (Teleostei: Channidae) | author = Britz, Ralf]
** "Channa panaw" Musikasinthorn, 1998.
** "Channa pleurophthalmus" (Bleeker, 1851).
** "Channa pulchra" Britz, 2007.
** Spotted snakehead, "Channa punctata" (Bloch, 1793).
** Assamese snakehead, "Channa stewartii" (Playfair, 1867).
** Snakehead murrel, "Channa striata" (Bloch, 1793).
* Genus "Eochanna"
** "Eochanna chorlakkiensis (Roe, 1991).
* Genus "Parachanna"
** "Parachanna africana" (Steindachner, 1879).
** "Parachanna insignis" (Sauvage, 1884).
** †"Parachanna fayumensis" Murray, 2006. (fossil)
** Obscure snakehead, "Parachanna obscura" (Günther, 1861).

Prehistory and evolution

Channidae are well-represented in the fossil record and known from numerous specimens. Research indicates that snakeheads likely originated in the south Himalayan region (modern-day Pakistan) at least 50 million years ago, during the Early Eocene epoch. By 17 Ma, during the Early Miocene, Channidae had spread into western and central Eurasia, and by 8 Ma, during the late Tortonian, they could be found throughout Africa and East Asia. cite journal |last=Böhme |first=Madelaine |year=2004 |month=May |title=Migration history of air-breathing fishes reveals Neogene atmospheric circulation patterns |journal=Geology |volume=32 |issue=5 |pages=393–396 |url=http://www.gsajournals.org/perlserv/?request=get-abstract&doi=10.1130%2FG20316.1 |accessdate=2008-07-09] 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 climactic patterns. cite journal |last=Böhme |first=Madelaine |year=2004 |month=May |title=Migration history of air-breathing fishes reveals Neogene atmospheric circulation patterns |journal=Geology |volume=32 |issue=5 |pages=393–396 |url=http://www.gsajournals.org/perlserv/?request=get-abstract&doi=10.1130%2FG20316.1 |accessdate=2008-07-09]

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. 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 on wet land to other bodies of water by wriggling with their body and fins.

Snakeheads became a national news topic in the US because of the appearance of northern snakeheads spawning in a Maryland pond in 2002. [http://news.nationalgeographic.com/news/2002/07/0702_020702_snakehead.html Maryland Wages War on Invasive Walking Fish] Hillary Mayell. "National Geographic", 02 July 2002.] Northern snakeheads became permanently established in the Potomac River around 2004, [http://www.baltimoresun.com/sports/outdoors/bal-md.snakeheads27apr27,0,6241227.story Potomac snakeheads not related to others] Associated Press, "Baltimore Sun", 27 April 2007.] and possibly established in Florida. Apparently non-established specimens have been found in Flushing Meadows-Corona Park, New York, as well as Wawayanda, New York [cite news|url=http://www.recordonline.com/apps/pbcs.dll/article?AID=/20080806/NEWS/808060331|title=DEC sprays poison to kill snakeheads|publisher="The Times Herald Record"|date=August 6, 2008|author=Yakin, Heather] , two ponds outside Philadelphia, Pennsylvania a pond in Massachusetts, and reservoirs in California and North Carolina.

They are prohibited in several other countries,Fact|date=July 2007 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 [http://cars.er.usgs.gov/circ_1251_courtenay.pdf that of Prof. W. Courtenay] .

Other Sightings in the U.S.

In what was determined by the Army Corps of Engineers to be an cite web |url=http://abclocal.go.com/wls/story?section=News&id=2277918&ft=med |title=isolated incident , a fisherman caught a single snakehead on October 9, 2004 while fishing from Lake Michigan at Burnham Harbor in Chicago, Illinois. Snakeheads have also been spotted in Alabama, Arkansas,
California, Colorado, Florida, Maryland, Georgia, Hawaii, Idaho, Kentucky, Mississippi, New York,
Nevada, North Carolina, Oregon, Pennsylvania, South Carolina, Texas, Utah, Wisconsin, and
Washington. cite news
first = Jeffrey
last = Kluger
title = Fish Tale
url = http://www.time.com/time/magazine/article/0,9171,1002979-1,00.html
work = Time Magazine
date = 2002-08-05
accessdate = 2008-02-22 ] [http://www.epa.gov/EPA-IMPACT/2002/October/Day-04/i25337.htm Injurious Wildlife Species; Snakeheads] Environmental Protection Agency. Retrieved 17 February 2008.]

ightings in the UK

On February 19, 2008 it was reported that a snakehead weighing almost lb to kg|num=3|precision=1 was caught in the River Witham near North Hykeham, Lincolnshire. The "Angler's Mail" confirmed it was a giant snakehead "Channa micropeltes". [cite news
first = Paul
last = Stokes
title = Fish that attacks people caught in Witham
url = http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/02/20/eafish120.xml
work = Telegraph
date = 2008-02-20
accessdate = 2008-02-22 ] [cite news
first = Jeffrey
last = Kluger
title = Man-eating 'psycho' fish found in UK
url = http://www.metro.co.uk/news/article.html?in_article_id=100114&in_page_id=34
work = Metro.co.uk
publisher = Associated Newspapers
date = 2008-02-19
accessdate = 2008-02-22 ] This subsequently turned out to be a hoax. [cite journal|last=Clarke|first=Matt|title=Snakehead catch 'a hoax'|journal=Practical Fishkeeping|date=April 2008] The "Norfolk Eastern Daily Press" reported in March: [cite news
url = http://new.edp24.co.uk/content/sport/story.aspx?brand=EDPOnline&category=Sport&tBrand=EDPOnline&tCategory=Sport&itemid=NOED04%20Mar%202008%2020%3A36%3A20%3A940
title = Picture perfect haul delights Harris
first= Roy | last= Webster
work= Norfolk Eastern Daily Press
date = 2008-03-05
accessdate = 2008-04-01 ] quote|Expert opinion from fish scientists insisted this warm water species could never survive in the icy Lincolnshire river for more than a few seconds. It has since been discovered the snakehead was actually dead laying in a Lincoln street and the finder preserved it in a domestic freezer until the following weekend when the misleading pictures were taken.

Removal

Snakeheads may be exterminated by applying the herbicides diquat dibromide and glyphosate (tradenames such as Roundup, Rodeo) to ponds to eliminate aquatic vegetation. The death of aquatic plants causes dissolved oxygen levels to drop, and a subsequent fish kill occurs.Fact|date=July 2007

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.

Notes

References

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External links

* [http://fishing.about.com/cs/fishfactsinfo/a/aa092703a.htm About.com's article on Snakeheads]
* [http://www.snakeheads.org snakeheads.org] world's largest website for snakeheads
* [http://www.scinet.cc/articles/northern-snakehead/frankenfish.html Overview of Northern Snakehead biology]
* [http://www.biodiversitypartners.org/state/fl/snakehead.shtml Student article on Snakehead problem in Florida]
* [http://www.mauricemartin.net/snakehead.htm Fish or Foul: Snakeheads near Washington, D.C., and the people who love them]