Anabantoidei

Taxobox
name = Anabantoidei

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image_width = 250px
image_caption = Dwarf gourami ("Colisa lalia")
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Perciformes
subordo = Anabantoidei
subdivision_ranks = FamiliesITIS|ID=172582|taxon=Anabantoidei|date=30 June|year=2006]
subdivision =
Anabantidae (climbing gouramies)
Helostomatidae (kissing gouramies)
Osphronemidae (gouramies)

The Anabantoidei is a suborder of perciform ray-finned freshwater fishes distinguished by their possession of a lung-like labyrinth organ, which enables them to breathe air. The fishes in the Anabantoidei suborder are known as anabantoids or labyrinth fishes. Some labyrinth fishes are important food fish and many others, such as the Siamese fighting fish and paradise fish, are popular as aquarium fishes.

Labyrinth organ

The labyrinth organ, a defining characteristic of fishes in the suborder Anabantoidei, is a much-folded suprabranchial accessory breathing organ. It is formed by vascularized expansion of the epibranchial bone of the first gill arch and used for respiration in air. Pinter, H. (1986). Labyrinth Fish. Barron's Educational Series, Inc., ISBN 0-8120-5635-3]

Or more simply put, this organ allows labyrinth fish to take in oxygen directly from the air, instead of taking it from the water they reside in through use of gills. The labyrinth organ helps the inhaled oxygen to be absorbed into the bloodstream. As a result, labyrinth fishes can survive for a short period of time out of water, as they can inhale the air around them, provided they stay moist.

Labyrinth fish, however, are not born with functional labyrinth organs. The development of the organ is gradual and most labyrinth fish fry breathe entirely with their gills and develop the labyrinth organs when they grow older. ]

Range

Labyrinth fishes are endemic to freshwaters of Asia and Africa. In Asia, they are found throughout East, Southeast, and South Asia, especially but not exclusively in the warm, slow-flowing, low-oxygenated waters. In Africa, significantly smaller numbers of labyrinth fishes can be found in the lower half of the continent, with concentrations in the rainforest waters. ]

The characteristics of the fish habitats are indicators of the size of the labyrinth organ, as the organ size is negatively correlated with the level of oxygen in the waters. Species native to low oxygenated waters are more likely to have larger and more complex labyrinth organs than species found in fast-flowing, high-oxygenated waters. ]

Behavior

In general, the labyrinth fishes are carnivores that eat small aquatic organisms and carrion. Some species will also consume algae and water plants. Most fishes are active during daytime but several African species feed at twilight and night. Species of the genus "Colisa" can spit water toward insects to bring them down to the water surface, similarly to the archerfish behavior. ]

Labyrinth fishes are well-known for their bubble nesting behavior, although some species do not build bubble nests and employ other methods of brooding. For the bubble nesting species, males establish nesting territories and defend them vigorously. As the name suggests, the bubble nests are floating bubbles coated with oral mucus from the males. Typically, the male bubble nesters stay nearby to guard the nests and constantly retrieve any falling eggs and fry to the nest. Some "Betta" species from fast-flowing waters, however, are mouthbrooders and do not build bubble nests. [cite web | url=http://www.bettysplendens.com/articles/page.imp?articleid=1272 |title=A look inside the bubblenest|author=Parnell, V. (2006) | accessdate=2006-12-23] In these species, males hold the eggs and fry in their mouth and release the free-swimming fry about a week to ten days after spawning.

Anabantoids as food fish

Several labyrinth fishes are important food sources in their native countries. The giant gourami in particular, is highly valued as food fish, due to its size and tender flesh with few spines. [Chanphong, Jitkasem. (1995). [http://www.fisheries.go.th/aahri/Health_new/AAHRI/AAHRI/Topics/Newsletter/art8.htm Diseases of Giant Gourami, Osphronemus goramy (Lacepede)] . "The Aquatic Animal Health Research Institute Newsletter" 4(1).] This species is farmed extensively in Thailand and other Southeast Asian countries and was intentionally introduced in tropical and subtropical waters around the world. During the colonial period, the French attempted to introduce this fish to many of their territories. Although an attempt to introduce a population in southern France failed, the giant gourami became well established in other French colonies. ] In the late 1880s, there were unsuccessful attempts to introduce the giant gourami to California waters as food fish. In the 1950s, the giant gourami population was established in Hawaii. [Nico, L. (2006). " [http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=798 Osphronemus gorami] ". USGS Nonindigenous Aquatic Species Database, Gainesville, FL.]

Other smaller labyrinth fishes, such as the climbing perch, the kissing gourami, the snakeskin gourami, and other gouramies of the genus "Trichogaster" are local food fishes in Southeast Asia. ] In some areas, the fishes are processed into salted and dried food. [cite web|url=http://filaman.ifm-geomar.de/summary/SpeciesSummary.php?id=4675|title=Trichogaster trichopterus |author=Froese, R. and D. Pauly. Editors.|publisher=FishBase|accessdate=2006-12-23]

Anabantoids as aquarium fish

The Siamese fighting fish is perhaps the most popular labyrinth fish in the aquarium trade. The paradise fish also has a long aquarium history and was one of the first aquarium fishes introduced to the West. ] Many species of gouramies, particular the three spot gourami and the dwarf gourami, are commercially bred for the trade and several color morphs are commonly available. Because of their capability to utilize atmospheric oxygen, these fishes generally are not so dependent on a form of aeration in their tank, as they can rise to the surface of the water and take a breath. This makes them a very hardy fish that can survive in less-than-ideal tank conditions. Unfortunately, because of this quality, labyrinth fishes are often kept in small confined areas, or even tiny cups in the case of the Siamese fighting fish. Many of the labyrinth fishes are peaceful and do well in most community tanks. However, individual males, especially the Siamese fighting fish and paradise fish, are territorial towards each other. So, a large aquarium with only one male per tank is ideal to reduce aggression.

References

External links

* [http://www.mrcmekong.org/pdf/Anabantoids.pdf Anabantoids (PDF)] - definition of "labyrinth fish"