Asian arowana: Difference between revisions
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==External links== |
==External links== |
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*[http://www.arowanaclub.com www. |
*[http://www.arowanaclub.com www.arowanaclub.com] |
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*[http://http://www.arowanaclub.com/assets/AroParts/ArowanaParts.htm Parts of an Asian Arowana] |
*[http://http://www.arowanaclub.com/assets/AroParts/ArowanaParts.htm Parts of an Asian Arowana] |
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Revision as of 16:21, 2 September 2006
| Asian arowanas | |
|---|---|
| File:Arowanacele4.jpg | |
| Super red arowana, Scleropages legendrei | |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | |
| Order: | |
| Family: | |
| Genus: | |
| Species: | S. aureus
S. formosus S. legendrei S. macrocephalus |
| Binomial name | |
| Scleropages aureus Pouyaud, Sudarto and Teugels, 2003
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| Scleropages formosus | |
| Scleropages legendrei Pouyaud, Sudarto and Teugels, 2003
| |
| Scleropages macrocephalus Pouyaud, Sudarto and Teugels, 2003
| |
The Asian arowanas are four species of closely related freshwater fish in the genus Scleropages.[2][3] They have several other common names, including Asian bonytongue, dragon fish, and a number of names specific to different varieties (see Species below). Until 2003, the Asian arowana was considered a single species with several distinct populations, but recent research has shown these populations comprise at least four separate species.[2]
Native to Southeast Asia, Asian arowanas inhabit blackwater rivers, slow-moving waters flowing through forested swamps and wetlands. Adults are piscivorous, with juveniles feeding on insects.[4]
These popular aquarium fish have special cultural significance in areas influenced by Chinese culture. The name dragon fish stems from their resemblance to the mythical Chinese dragon. This popularity has had both positive and negative effects on their status as endangered species.
Origin
All osteoglossids are highly adapted to freshwater and are incapable of surviving in the ocean; therefore, the spread of Asian arowanas throughout the islands of southeast Asia suggests they diverged from other osteoglossids before the continental breakup was complete. Confirmation has come from genetic studies, which have shown that the ancestor of the Asian arowanas diverged from the ancestor of the Australian arowanas, S. jardinii and S. leichardti, about 140 million years ago, during the Early Cretaceous period. This divergence took place in the eastern margin of Gondwanaland, with the ancestors of Asian arowanas carried on the Indian subcontinent or smaller landmasses into Asia. The morphological similarity of all six species shows that little evolutionary change has taken place recently for these ancient fish.[5][6]
Species
The first description of these species was published between 1839 and 1844 (1844 is the date commonly cited) by German naturalists Salomon Müller and Hermann Schlegel, under the name Osteoglossum formosum[citation needed]. Later this species was placed in Scleropages with the name S. formosus.[7] Prior to 2003, all Asian arowanas were placed in this species, with several distinct color varieties recognized. These strains occur naturally and are based on geographic region; they include the following:
- The green is the most common variety, found in Vietnam, Myanmar, Thailand, and Malaysia.
- The silver Asian (not to be confused with the silver arowana, Osteoglossum bicirrhosum) is considered part of the green variety by some. It has two subvarieties, the "grey tail silver" or "Pinoh arowana," and the "yellow tail silver," each found in a different part of the island of Borneo in Indonesia.
- The red-tailed golden is found in northern Sumatra, Indonesia.
- The gold crossback, blue Malayan, or Bukit Merah blue is native to the state of Pahang and Bukit Merah area in Perak, Malaysia.
- The red, super red, blood red, or chili red is known only from the upper part of the Kapuas River in western Borneo, Indonesia.
However, in 2003, Scleropages formosus was redescribed and three new species, formerly considered populations of that species, were described. This classification was based on both morphology and genetics.
- Scleropages formosus was redescribed to include only the strain known as the green arowana.
- Scleropages macrocephalus describes the silver Asian arowana.
- Scleropages aureus describes the red-tailed golden arowana.
- Scleropages legendrei describes the super red arowana.
This study did not include any specimens of the gold crossback strain, which for now remains included in S. formosus.[2]
Asian arowanas are prized aquarium fish in some parts of the world, and the various color varieties have differing values to hobbyists. The super red arowana is regarded by many to be of greatest beauty because red is considered an auspicious color, according to some local cultures (see Cultural Beliefs below). Each color variety has variations among different localities. For instance, the gold crossback may have various base colours, including blue, gold, green, turquoise, and purple. Hobbyists consider the highest grade of the gold crossback to be the full gold crossback (frameless gold), which originated from the Sungai Gedong river system.
Descriptions
Like all Scleropages, Asian arowanas have long bodies; large pectoral fins; dorsal and anal fins located far back on the body; and a much larger caudal fin than that of their South American relative, the silver arowana, Osteoglossum bicirrhosum. Their scales are large and, in some species, metallic colored. The scales have a distinctive network of raised ribs. These mouthbrooding carnivores have paired barbels on the end of the lower jaw.
All Asian arowanas are distinguished from Australian congenerics S. jardinii and S. leichardti by having fewer (21-26) lateral line scales (versus 32-36), longer pectoral and pelvic fins, and a longer anterior snout.
Green arowana
This fish is dark green on its back, silvery or golden green on its sides, and silvery or whitish on its ventral surface, with dark greenish or bluish patches visible through the lateral scales. In mature fish, the top of the eye and the head behind the eye are bright emerald. The green arowana is the only one of the four species to have the combination of a narrow head and long upper jaw (maxillary); it also has a short anal fin.
Silver Asian arowana
Both grey-tailed and yellow-tailed individuals are dark grey on the back and silver on the sides, with dark ring patches on the lateral scales and a silvery or whitish belly. In yellow-tailed specimens, the fin membranes are yellowish with dark grey rays. In grey-tailed specimens, the fins are uniform dark grey.
Silver Asian arowanas are distinguished by having the broadest heads of all the Asian arowanas. They also have long maxillaries and short anal fins.
Red-tailed golden arowana
Mature individuals have brilliant metallic gold lateral scales, opercula, bellies, and pectoral and pelvic fin membranes, although the back remains dark in color. In juveniles the areas destined to develop golden color start out metallic silver. The anal fin and the bottom portion of the caudal fin are light brown to dark red in color.
Red-tailed golden arowanas have shorter upper jaws (maxillaries) than green and silver Asian arowanas, as well as the longest anal fins of the four species.
Super red arowana
When mature, the opercula, lateral scales, and fin membranes of these fishes are metallic red, with the exact hue varying from gold-tinged to deep red. The back is dark brown. In juveniles, the darker the dorsal coloration, the deeper the red hue will be on maturity.
Red arowanas have the shortest maxillaries of the four species as well as short anal fins.[2]
Gold crossback
The gold crossback arowana is currently placed within S. formosus along with the green arowana. Mature specimens are distinguished in terms of color from the red-tailed golden arowanas by having metallic gold crossing the back completely. This variety also lacks the reddish fins of the red-tailed golden. No study of the morphological differences between this variety and other Asian arowanas is currently available.[8]
Cultural beliefs
Asian arowanas are considered "lucky" fish by many people, particularly those from Asian cultures. The species' large metallic scales and double barbels are features shared by the Chinese dragon, a good luck symbol; some people believe the Asian arowana is a reincarnation of the dragon. In addition, positive Feng Shui associations with water and the colors red and gold make these fishes popular for aquariums.
One belief associated with Asian arowanas is that while water is a place where chi gathers, it is naturally a source of yin energy and must contain an "auspicious" fish such as an arowana in order to have balancing yang energy.[8] Another is that a fish can preserve its owner from death by dying itself.[9] A third belief is that the fish can ward off evil spirits if kept in the home.[10]
Conservation status
The Asian arowanas are listed as endangered by the 2006 IUCN Red List, although it was last evaluated in 1996.[1] International trade in these fishes is controlled under the Convention on the International Trade in Endangered Species of Wild Flora and Fauna (CITES), under which it was placed on Appendix I, the most restrictive category, in 1975.[11][12] There are twenty three registered CITES breeders in Asia and the specimens they generate can be imported into several nations, although not the United States.
In light of the recent reclassification into four species, conservation status needs to be reconsidered. All are probably endangered, but some species are more critically endangered than others.[2] In addition, S. formosus has not been evaluated by IUCN since 1996.
These species' wild stocks have been depleted largely due to their high value as aquarium fish. Followers of Feng Shui may pay thousands of dollars for one of these animals.
Beginning in 1989, CITES began allowing Asian arowanas to be traded, provided they were bred in captivity on a fish farm. Trade in wild-caught specimens is still prohibited.[13] The extent of illegal trade in Asian arowanas is still unknown.
Genetic fingerprinting has been used to assess the genetic diversity of a captive population at a Singapore fish farm in order to improve the management of this species.[14]
Asian arowanas as aquarium fish
Asian arowanas are large fish and require a large aquarium. They are carnivores and should be fed a high-quality diet of meaty food, such as shrimp and crickets. These territorial fish should not be kept with other Scleropages except in a very large aquarium. Prized specimens can cost thousands of dollars. Greens are the least valuable, followed by red-tail goldens, crossback goldens, and reds.
Asian arowanas are not known to breed well in aquariums. Serious breeders use large outdoor ponds. [12]
References
- ^ a b Template:IUCN2006
- ^ a b c d e Pouyaud, Laurent (2003). "The Different Colour Varieties of the Asian Arowana Scleropages formosus (Osteoglossidae) are distinct species: Morphologic and genetic evidences". Cybium. 27 (4): 287–305.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ "Scleropages formosus". Integrated Taxonomic Information System. 11 March.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ Froese, Rainer; Pauly, Daniel (eds.) (2006). "Scleropages formosus" in FishBase. 3 2006 version.
- ^ Kumazawa, Yoshinori (2000). "Molecular Phylogeny of Osteoglossoids: A New Model for Gondwanian Origin and Plate Tectonic Transportation of the Asian Arowana". Molecular Biology and Evolution. 17 (12). Retrieved 2006-07-12.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Kumazawa, Yoshinori (2003). "The reason the freshwater fish arowana live across the sea". Quarterly Journal Biohistory (Winter). Retrieved 2006-07-02.
- ^ "Catalog of Fishes (online version)". California Academy of Sciences. 2006-04-17. pp. Search results for Osteoglossum formosum. Retrieved 2006-08-15.
- ^ a b "World of Asian Arowana". Unoaquatic Arowana Group. 1999. Retrieved 2006-08-05.
- ^ "Superstitious Bangaloreans eat Arowana fish". Hindustan Times. 2005-11-10. Retrieved 2006-05-10.
{{cite news}}: Check date values in:|date=(help) - ^ "Chinese Belief". Dragonfish Industry. 1997. Retrieved 2006-05-10.
- ^ "Appendices I, II and III". CITES. 2005-06-23. Retrieved 2006-05-10.
{{cite web}}: Check date values in:|date=(help) - ^ a b "Scleropages formosus (Asian Arowana)". Fishindex.com. Retrieved 2006-07-01.
- ^ Cheng Lee. "The Fate of the Asian Arowana in the Hands of the Aquarium Industry".
- ^ Fernando, A.A. (1997). "DNA fingerprinting: application to conservation of the CITES-listed dragon fish, Scleropages formosus (Osteoglossidae)". Aquarium Sciences and Conservation. 1 (2): 91–104. Retrieved 2006-05-10.
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