Arowanas
Arowanas are freshwater bony fish of the family Osteoglossidae, sometimes known as "Bony tongues." 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 'bony tongues' 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.
Classification
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.
Habits
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 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 a contender for the world's largest freshwater fish.
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.
Extant 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.
Subfamily Heterotidinae
Genus Arapaima
A. gigas (Cuvier, 1829) - the Pirarucu or Arapaima
Genus Heterotis
H. niloticus (Cuvier, 1829) - the African Arowana
Subfamily Osteoglossinae
Genus Osteoglossum (Cuvier, 1829)
O. bicirrhosum (Cuvier, 1829) - the Silver Arowana
O. ferreirai Kanazawa, 1966 - the Black Arowana
Genus Scleropages
S. aureus (Pouyad, Sudarto & Teugels, 2003) - the Red-Tailed Golden Arowana
S. formosus (Schlegel & M?ller, 1844)- the Asian Arowana, Asian Bonytongue or Green Arowana
S. jardinii (Saville-Kent, 1892)- the Australian Arowana, Silver Barramundi or Northern Saratoga
S. legendrei (Pouyad, Sudarto & Teugels, 2003) - the Super Red Arowana
S. leichardti G?nther, 1864 - the Australian Arowana, Spotted Barramundi, or Spotted Saratoga
S. macrocephalus (Pouyad, Sudarto & Teugels, 2003)
Fossil record
At least five fish paleospecies, known only from fossils, are classifed 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 order Osteoglossomorpha. Osteoglossomorph fossils have been found on all continents except Antarctica. (Guo-Qing & Wilson, 1998)
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. (Frickhinger, 1995)
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. (Newbreya and Bozekb, 2000).
Genus Phareodus
This genus includes at least two species, P. testis (Leidy, 1873) and P. encaustus. 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. (Frickhinger, 1995)
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 pectorals. It is synonymous with Dapedoglossus. (Frickhinger, 1995)
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