Arowana

Arowana
Silver arowana, Osteoglossum bicirrhosum
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Osteoglossiformes
Family:	Osteoglossidae
Genera
Subfamily Heterotidinae  Arapaima  Heterotis Subfamily Osteoglossinae  Osteoglossum  †Phareodus  Scleropages

Arowanas are freshwater bony fish of the family Osteoglossidae, sometimes known as "bonytongues". In this family of fishes, the head is bony and the elongate body is covered by large, heavy scales, with a mosaic pattern of canals. The dorsal and the anal fins have soft rays and are long based, while the pectoral and ventral fins are small. The name "bonytongues" is derived from a toothed bone on the floor of the mouth, the "tongue", equipped with teeth that bite against teeth on the roof of the mouth. The fish can obtain oxygen from air by sucking it into the swim bladder, which is lined with capillaries like lung tissue. The arapaima is an "obligatory air breather".^[1]

Classification and distribution

Osteoglossids are basal (primitive) fish from the lower Tertiary and are placed in the actinopterygiid order Osteoglossiformes. There are ten described living species: three from South America, one from Africa, four from Asia, and the remaining two from Australia.

Osteoglossidae is the only exclusively freshwater fish family found on both sides of the Wallace Line.^[2] This may be explained by the fact that Asian arowanas (S. formosus) diverged from the Australian Scleropages, S. jardinii and S. leichardti, about 140 million years ago, making it likely that Asian arowanas were carried to Asia on the Indian subcontinent.^[3][4]

Behavior

Osteoglossids are carnivorous, often being specialized surface feeders. They are excellent jumpers; it has been reported that Osteoglossum species have been seen leaping more than 6 feet (almost 2 metres) from the water surface to pick off insects and birds from overhanging branches in South America, hence the nickname "water monkeys". Arowanas have been rumored to capture prey as large as low flying bats and small birds. All species are large, and the arapaima is one of the world's largest freshwater fish, at 2.5 metres (8.2 ft) in length.^[5] Arowana typically grow to around 3 to 4 feet in captivity.

Several species of osteoglossid exhibit extensive parental care. They build nests and protect the young after they hatch. Some species are mouthbrooders, the parents holding sometimes hundreds of eggs in their mouths. The young may make several tentative trips outside the parent's mouth to investigate the surroundings before leaving permanently.^[5]

In the aquarium

Arowanas tend to merge in groups of five to eight; any fewer may show an excess of dominance and aggression. Some compatible fish often partnered with this fish are clown knifefish, pacu, oscars, plecostomus, jaguar cichlids, green terrors, gar and any other semi-aggressive fish that cannot fit in the arowana's mouth.

Australian species are best kept singly in aquaria.^[6][7]

Folklore

This section does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (August 2009)

This storefront in the International District of Seattle, Washington, is an example of the depiction of arowanas in folk art.

For the Chinese and those of related cultures, the dragon is a symbol of good luck and prosperity. In the eyes of the Chinese, the dragon fish has the appearance and majesty of the Chinese Dragon, especially the large scales and barbels.

Arowanas are also used for feng shui to bring good luck. As per the feng shui belief Arowanas are believed to possess capabilities to distinguish between an enemy and a well-wisher. It is believed that if the arowana in the aquarium shows aggression toward the visitor to house, he is an enemy; and if the fish remains calm, the visitor is a well-wisher.

Species

This section's factual accuracy is disputed. Please see the relevant discussion on the talk page. (November 2008)

The family contains two subfamilies, Heterotidinae and Osteoglossinae, with all but two of the ten extant species being members of the latter. Species are given with one or more prominent common names.

Family Osteoglossidae

• Subfamily Heterotidinae
  • Genus Arapaima
    • Arapaima or pirarucu, Arapaima gigas (Cuvier, 1829)
  • Genus Heterotis
    • African arowana, Heterotis niloticus (Cuvier, 1829)
• Subfamily Osteoglossinae
  • Genus Osteoglossum (Cuvier, 1829)
    • Silver arowana, Osteoglossum bicirrhosum (Cuvier, 1829)
    • Black arowana, Osteoglossum ferreirai Kanazawa, 1966
  • Genus Scleropages
    • Red-tailed golden arowana Scleropages aureus (Pouyad, Sudarto & Teugels, 2003)
    • Green arowana or gold crossback arowana, Scleropages formosus (Schlegel & Müller, 1844)
    • Gulf saratoga, red saratoga or northern spotted barramundi, Scleropages jardinii ^‡ (Saville-Kent, 1892)
    • Red arowana, super red arowana, or chili red arowana, Scleropages legendrei (Pouyad, Sudarto & Teugels, 2003)
    • Saratoga, silver saratoga or spotted barramundi, Scleropages leichardti ^‡ Günther, 1864
    • Silver Asian arowana, Scleropages macrocephalus (Pouyad, Sudarto & Teugels, 2003)

^‡This species is one of two sometimes called the Australian arowana or Australian bonytongue.

A genetic study shows that the lineage leading to the arapaima and African arowana diverged about 220 million years ago, during the Late Triassic; the lineage leading to the silver and black arowanas of South America diverged about 170 million years ago, during the Middle Jurassic. The lineage leading to the Australian arowanas diverged from that leading to the Asian arowanas about 140 million years ago, during the Early Cretaceous.^[4]

Fossil record

At least five extinct genera, known only from fossils, are classified as Osteoglossids; these date back at least as far as the Late Cretaceous. Other fossils from as far back as the Late Jurassic or Early Cretaceous are widely considered to belong to the arowana superorder Osteoglossomorpha. Osteoglossomorph fossils have been found on all continents except Antarctica.^[8]

Genus Brychaetus

Brychaetus muelleri (Agassiz, 1845) is known from the Late Cretaceous to the Paleocene. Its fossils have been found in Europe, North America, and northern Africa. This freshwater fish had very long, blunt teeth. Platops and Pomphractus are synonyms.^[9]

Genus Joffrichthys

This North American genus includes two species, J. symmetropterus and J. triangulpterus. The latter species is known from the Paleocene of the Sentinel Butte Formation of North Dakota, U.S.A.^[10]

Genus Phareodus

Phareodus testis fossil

• P. encaustus (syn, P. acutus)^[11]
• P. muelleri
• P. queenslandicus
• P. testis

This genus includes at least four species^[11], P. testis (Leidy, 1873) and P. encaustus of North America, P. muelleri of Europe, and P. queenslandicus of Australia. Representatives have been found from the middle Eocene to the Oligocene of Australia and North America, including the Green River Formation in Wyoming, U.S.A.^[9]

P. testis was a freshwater fish with an oval outline, a small head, and a slightly pointed snout. Its dorsal and anal fins were situated posteriorly, with the anal fin being larger. Its caudal fin was slightly forked. It had small pelvic fins but long, narrow pectoral fins. It is synonymous with Dapedoglossus.^[9]

References

• Lim, Eugene (2006). "Arowana / Arawana" (article). Aquarium Lore. http://aquariumlore.blogspot.com/2006/04/arowana.html. Retrieved April 20, 2006. 

External links

• Fishbase article