Arowana [You must be registered and logged in to see this image.]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"
Classification and distributionOsteoglossids 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.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.
BehaviorOsteoglossids 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 meters) 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.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.
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.
Folklore 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 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
o Genus Arapaima
Arapaima or pirarucu, Arapaima gigas (Cuvier, 1829)
o Genus Heterotis
African arowana, Heterotis niloticus (Cuvier, 1829)
•
Subfamily Osteoglossinae
o Genus Osteoglossum (Cuvier, 1829)
Silver arowana, Osteoglossum bicirrhosum (Cuvier, 1829)
Black arowana, Osteoglossum ferreirai Kanazawa, 1966
o 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.
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.
Tue Apr 06, 2010 12:52 am
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