Anabantoidei

(vertebrate zoology) A suborder of fresh-water labyrinth fishes in the order Perciformes.

(Labyrinth fishes)

Class: Actinopterygii

Order: Perciformes

Suborder: Anabantoidei

Number of families: 3

Evolution and systematics

The labyrinth fishes were first recognized as a natural assemblage by Cuvier and Valenciennes in 1831, but included the Channidae (snakeheads), in addition to the current family Anabantoidei. Bleeker (1859, 1879) added the luciocephalids (pikeheads) to this group. Jordan (1923) recognized six families, including Luciocephalus and Channidae. In 1963, Liem restricted the anabantoids to the families Anabantidae, Helostomatidae, Osphronemidae, and Belontiidae, thus removing Luciocephalus and the channids. In 1983 Lauder and Liem included Luciocephalus, in its own family Luciocephalidae, again in the anabantoids as the sister group to all remaining labyrinth fishes. Britz (1994, 1995), and Britz et al. (1995) demonstrated that there are no differences between Liem's families Belontiidae and Osphronemidae and that Luciocephalus is deeply nested within Liem's belontiids. The family name Osphronemidae applies for this monophyletic assemblage. The suborder Anabantoidei is thus divided into three families, Anabantidae, Helostomatidae, and Osphronemidae. The latter family is the sister group of the former two, and it is further subdivided into the subfamilies Belontiinae (only Belontia, two spp.); Osphroneminae (only Osphronemus, four spp.); Luciocephalinae (Trichogaster, four spp.; Colisa, four spp.; Parasphaerichthys, two spp.; Ctenops, one sp.; Sphaerichthys, four spp.; Luciocephalus, one sp., one undescribed sp.); and Macropodinae (Macropodus, five spp.; Pseudosphromenus, two spp.; Malpulutta, one sp.; Parosphromenus, 10 spp., some undescribed; Trichopsis, three spp.; Betta, 43 spp., some undescribed).

The closest relatives of anabantoids appear to be the Channidae. Based on the shared presence of parasphenoid teeth, both seem to form a larger monophyletic group with the badids and the genera Nandus and Pristolepis. The only unambiguous fossil anabantoid is a complete articulated skeleton from the Miocene epoch of Sumatra, assigned to Osphronemus goramy.

Physical characteristics

Anabantoids are minute (0.78 in; 20 mm) to large (23.6 in; 60 cm) percomorph fishes with a suprabranchial organ as accessory air-breathing organ. This organ consists of the suprabranchial chamber above the gill arches that houses the modified first epibranchial, termed the labyrinth. The labyrinth may have a highly complex three-dimensional shape in some species (Anabas and Osphronemus). Both the labyrinth and the wall of the suprabranchial chamber are lined with respiratory epithelium. The suprabranchial organ obtains blood from the first two afferent branchial arteries. Blood from the organ is collected in the two anterior efferent arteries that drain into the anterior cardinal vein, not into the dorsal aorta as in other teleosts. Basioccipital with paired articular processes that permit free movement with upper pharyngeal jaws. The last two characters are shared with the channids. In most anabantoids, the lacrimal and preopercular bones bear strong serrations; in anabantids, serrations occur in the subopercle, opercle bones, and sometimes the interopercle. (The name anabantids is vernacular for the family Anabantidae; anabantoids is the vernacular name for the suborder Anabantoidei.) All species except African anabantids and Helostoma have a exoccipital foramen medial to suprabranchial chamber, greatly enhancing hearing abilities. Most species are parasphenoid toothed, a unique derived character shared with channids, badids, Nandus, and Pristolepis. The swim bladder branches off posteriorly into two elongate diverticula that reach on either side of the hemal spines to the level of the parhypural. Many species are beautifully colored, with striking sexual dimorphism and dichromatism.

Distribution

Anabantoids occur in fresh waters of sub-Saharan Africa, and south and Southeast Asia. The genera Ctenopoma, Microctenopoma, and Sandelia occur only in Africa. The latter genus is confined to the Cape region and separated by a distributional gap from the other African anabantids. Most Asian species are widely distributed, but some have a greatly restricted distribution, such as Belontia signata and Malpulutta kretseri, known only from Ceylon, or Parosphromenus deissneri, Betta miniopinna, B. schalleri, B. burdigala, and B. chloropharynx, restricted to Banka Island in Indonesia. The northernmost distributed species is Macropodus ocellatus, from China and Korea.

Several species have been exported as food fishes or have been released accidentally from aquarium stocks to areas out-side their natural ranges.

Habitat

Numerous species of anabantoids prefer still bodies of water with abundant aquatic vegetation that are exposed to the sun, but others also live in cooler, faster, mountain streams. Most anabantoids survive in oxygen-depleted waters because of their suprabranchial organ and therefore have an advantage over most other teleosts.

Behavior

In general, anabantoids differ from most other teleosts in that they rise to the water surface at intervals to exchange the air in their suprabranchial organ. This exchange is mostly achieved by flooding the suprabranchial chamber with water that enters through the gill opening. The water pushes the air out of the chamber and the mouth, either before or upon reaching the water surface. The chamber refills with air breathed in at the surface. In a second mode, air is gulped from the surface without the prior release of air from the chamber. Engulfed air is then pressed into the chamber by swallowing movements and forces some air out of the chamber, which is released from the gill opening. The latter mode is used by adult Anabas testudineus in the water and during the overland excursions that gave the species its vernacular name, the climbing perch. In addition to the climbing perch, at least one other anabantid species, the African Ctenopoma multispinis actively leaves the water and travels over land to nearby bodies of water.

Species of the genus Colisa show a behavior reminiscent of the spitting of the archerfishes (Toxotes jaculatrix). At least in captivity, representatives of Colisa spit a series of small droplets of water toward prey items, such as small invertebrates, above the water level to wash them down to the surface where they are taken by the fish.

Species of the genus Trichopsis are known for their ability to produce croaking sounds, hence their name, croaking gourami. These sounds are produced with their pectoral fins. To create the sounds, enlarged areas of tendons from the pectoral fin musculature are moved across bony knobs on some of the pectoral fin rays. The sound is enhanced by the suprabranchial chambers, which act as resonators.

All anabantoid species, except Sandelia capensis, show a typical, and for teleosts unusual, spawning clasp in which the male wraps around the female's body. The female is then either turned to the side or upside down when eggs are released. A similar clasp is also found in channids, badids, and Nandus, but not other nandids. A reduced clasp without turning of the female is shown by some mouth-brooding anabantoids.

Feeding ecology and diet

Anabantoids are diverse in regard to their feeding ecology and diet. There are extreme filter feeders, such as Helostoma, which feeds on small pelagic invertebrates and algae that are either filtered from the water or scraped off the substrate. Other species are omnivorous (Anabas, Osphronemus, Trichogaster, and Colisa), or have a diet with an emphasis on small invertebrates (Microctenopoma, Macropodus, Betta, and Trichopsis), but others prey on larger invertebrates and small fishes (Ctenopoma and Sandelia). Luciocephalus is a highly specialized predator of small fishes. Osphronemus exodon is an exclusively herbivorous species with external jaw teeth, which feeds on leaves of terrestrial plants, grasses, fruits, and flowers.

Reproductive biology

Although anabantoids are a fairly small percomorph group, their members exhibit a great variety of reproductive modes. The primitive mode, which occurs in Anabas, Ctenopoma, and Helostoma, is the absence of parental care with the release of several thousand small (ca. 0.04 in/1 mm), buoyant eggs that float due to a single large oil globule in the egg. After hatching, larvae retain the oil globule, which during development divides into two oil vesicles to the left and right of the chorda and is used as a floating organ. All species of the genus Microctenopoma and most osphronemids build bubble nests and guard primitively buoyant eggs and larvae. Bubble nests can consist of only a few bubbles, as in the tiny cave-brooding species of Parosphromenus, or be large. Mouth brooding has evolved at least twice among anabantoids, once in the lineage Ctenops, Sphaerichthys, and Luciocephalus, and again within the genus Betta.

Unusually for anabantoids, the two species of the purely South African genus Sandelia spawn on a substratum and have adhesive eggs. In groups with parental care, the number of eggs is usually smaller than in those without care, although several thousand eggs may be spawned in some species of Microctenopoma and Trichogaster. The number of eggs may range from 40 to several hundreds in most bubble nest builders, and from 20 to 200 in the mouth brooders. Egg size ranges from 0.03 in (0.7 mm) in Microctenopoma to 0.19 in (3 mm) in Luciocephalus.

Conservation status

Three anabantoid species are categorized as Critically Endangered by the IUCN, Betta miniopinna, Betta persephone, and Betta spilotogena. Sandelia bainsii, Parosphromenus harveyi, and Betta livida are categorized as Endangered. Another seven Betta species are categorized as Vulnerable, and the two Sri Lankan species Belontia signata and Malpulutta kretseri are categorized as Lower Risk.

Significance to humans

The larger species of anabantoid fishes are important as food fishes and feature in aquaculture in various parts of Asia. Many of the smaller, colorful anabantoids are very popular hardy ornamental fishes; up to several hundred U.S. dollars have been paid for a breeding pair of the conspicuously colored fighting fish Betta macrostoma, known as the Brunei beauty.

Species accounts

Resources

Cuvier, G., and A. Valenciennes. Histoire naturelle des poisons, Vol. 7. Paris/Strasbourg: Levrault, 1831.

Fuller, P. L., L. G. Nico, and J. D. Williams. Nonindigenous Fishes Introduced into Inland Waters of the United States. Bethesda, MD: American Fisheries Society, Special Publication 27, 1999.

Kottelat, M., A. J. Whitten, S. N. Kartikasari, and S. Wirjoatmodjo. Freshwater Fishes of Western Indonesia and Sulawesi. Jakarta: Periplus Editions, 1993.

Vierke, J. Labyrinthfische und verwandte Arten. Wuppertal-Elberfeld, Germany: Engelbert Pfriem Verlag, 1978.

Bleeker, P. "Memoires sur les poissons á pharyngiens labyrinthiformes de l'Inde archipelagique." Natuurk. Verh. Akad. Amsterdam. 19 (1879): 1–56. ——. "Over de platsing in het stelsel van de Luciocephaloiden." Natuurk. Tijdschr. Nederl. Ind. 20 (1859): 395–397.

Britz, R. "Ablaichverhalten und Maulbrutpflege bei Luciocephalus pulcher." Aquar. Terr. Ztschr. 47 (1994): 790–795. ——. "Egg Surface Structure and Larval Cement Glands in Nandid and Badid Fishes (Teleostei, Percomorpha), with Remarks on Phylogeny and Zoogeography." American Museum Novitates 3195 (1997): 1–17. ——. "The Genus Betta—Monophyly and Intrarelationships, with Remarks on the Subfamilies Macropodinae and Luciocephalinae (Teleostei: Osphronemidae)." Ichthyological Exploration of Freshwaters 12 (2001): 305–318. ——. "Ontogenetic Features of Luciocephalus (Perciformes, Anabantoidei) with a Revised Hypothesis of Anabantoid Intrarelationships." Zoological Journal of the Linnean Society 112 (1994): 491–508.

Britz, R., and J. A. Cambray. "Structure of Egg Surfaces and Attachment Organs in Anabantids." Ichthyological Exploration of Freshwaters 12 (2001): 267–288.

Britz, R., M. Kokoscha, and R. Riehl. "The Anabantoid Genera Ctenops, Luciocephalus, Parasphaerichthys, and Sphaerichthys (Teleostei: Perciformes) as a Monophyletic Group: Evidence from Egg Surface Structure and Reproductive Behavior." Japanese Journal of Ichthyology 42(1995): 71–79.

Hall, D. D., and R. J. Miller. "A Qualitative Study of Courtship and Reproductive Behavior in the Pearl Gourami, Trichogaster leeri." Behaviour 32 (1991): 70–84.

Jordan, D. S. "A Classification of Fishes Including Families and Genera as far as Known." Stanford Univ. Publ., Univ. Ser., Biol. Sci. 3 (1923): 77–243.

Kratochvil, H. "Beiträge zur Lautbiologie der Anabantoidei— Bau, Funktion und Entwicklung von lauterzeugenden Systemen." Zool. Jb. Physiol. 89 (1985): 203–255.

Lauder, G. V., and K. F. Liem. "The Evolution and Interrelationships of the Actinopterygian Fishes." Bulletin of the Museum for Comparative Zoology 150 (1983): 95–197. ——. "Prey Capture by Luciocephalus pulcher: Implications for Models of Jaw Protrusion in Teleost Fishes." Environmental Biology of Fishes 6 (1981): 257–268.

Liem, K. F. "The Comparative Osteology and Phylogeny of the Anabantoidei." Illinois Biological Monograph 30 (1963): 1–149.

Peters, H. M. "On the Mechanism of Air Ventilation in Anabantoids (Pisces: Teleostei)." Zoomorphology 89 (1978): 93–123.

Roberts, T. "Osphronemus exodon, a New Species of Giant Gouramy with Extraordinary Dentition from the Mekong." Natural History Bulletin of the Siam Society 42 (1994): 67–77. ——. "Systematic Revision of the Southeast Asian Anabantoid Fish Genus Osphronemus, with Descriptions of Two New Species." Ichthyological Exploration of Freshwaters 2(1992): 351–360.

Roxas, H. A., and A. F. Umali. "Fresh-Water Fish Farming in the Philippines." Philippine Journal of Science 63 (1937): 433–468.

Sanders, M. "Die fossilen Fische der alttertiären

Süsswasserablagerungen aus Mittel-Sumatra." Verh. Geol.Mijnbouw. Genootsch. Nderl. Kol. Geol. Ser., D. XI, 1ste St.(1937): 1–144.

Vierke, J. "Beiträge zur Ethologie und Phylogenie der Familie Belontiidae (Anabantoidei, Pisces)." Zeitschrift für Tierpsychologie 38 (1975): 163–199. ——. "Brutpflegestrategien bei Belontiiden (Pisces, Anabantoidei)." Bonn. Zool. Beitr. 42 (1991): 299–324.

Weber, H. "Die Sinnesfunktion der freien Bauchflossenstrahlen der Labyrinthfische (Anabantidae) und ihr Zusammenwirken mit den Augen." Ztschr. Vergl. Physiol. 47 (1963): 77–110.

California Academy of Sciences. 55 Concourse Drive, Golden Gate Park, San Francisco, CA 94118-4599 USA. Phone:(415) 750-7047. Fax: (415) 750-7148. E-mail: info@ calacademy.org Web site:

Food and Agriculture Organization of the United Nations (FAO) Fisheries. Viale delle Terme di Caracalla, Rome, 00100 Italy. Phone: 39 (06) 5705 1. Fax: 39 (06) 5705 3152. E-mail: FAO-HQ@fao.org Web site:

[Article by: Ralf Britz, PhD]

Anabantoidei
Dwarf gourami (Colisa lalia)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Perciformes Suborder: Anabantoidei
Families[1]
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. ^[2]

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. ^[2]

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. ^[2]

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. ^[2]

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.^[2]

A male Siamese fighting fish, Betta splendens, is building a bubble nest

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.^[3] 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

The giant gourami, Osphronemus goramy, is often raised in floating cages in central Thailand

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. ^[4] 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.^[2] 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.^[5]

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.^[2] In some areas, the fishes are processed into salted and dried food.^[6]

Anabantoids as aquarium fish

The Siamese fighting fish, Betta splendens, originally bred for staged fights, has become popular in the aquarium trade

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.^[2] 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 or only one male per tank is ideal to reduce aggression.

References

1. ^ Anabantoidei (TSN 172582). Integrated Taxonomic Information System. Accessed on 30 June 2006.
2. ^ ^{a b c d e f g h} Pinter, H. (1986). Labyrinth Fish. Barron's Educational Series, Inc., ISBN 0-8120-5635-3
3. ^ Parnell, V. (2006). A look inside the bubblenest. Retrieved on 2006-12-23.
4. ^ Chanphong, Jitkasem. (1995). Diseases of Giant Gourami, Osphronemus goramy (Lacepede). The Aquatic Animal Health Research Institute Newsletter 4(1).
5. ^ Nico, L. (2006). Osphronemus gorami. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
6. ^ Froese, R. and D. Pauly. Editors.. Trichogaster trichopterus. FishBase. Retrieved on 2006-12-23.

External links

• Anabantoids (PDF) - definition of "labyrinth fish"

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)