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Asian arowana

New Fish Tank Tips: Get and use an aquarium water test kit to monitor the aquarium nitrogen cycle. The best way to monitor this cycle is to purchase a freshwater or saltwater test kit that will test for ammonia, nitrites, nitrates and ph. Test the water coming out of your tap as well. This will arm you with more information when it comes time for those water changes.
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Asian arowana refers to several varieties of freshwater fish in the genus Scleropages. Some sources differentiate these varieties into multiple species,[2][3] while others consider the different strains to belong to a single species, Scleropages formosus.[4] They have several other common names, including Asian bonytongue, dragon fish, and a number of names specific to different varieties.

These popular aquarium fish have special cultural significance in areas influenced by Chinese culture. The name dragon fish stems from their resemblance to the Chinese dragon. This popularity has had both positive and negative effects on their status as endangered species.

Like all members of Osteoglossidae, Asian arowanas are highly adapted to fresh water and are incapable of surviving in the ocean. Therefore, their spread throughout the islands of southeast Asia suggests they diverged from other osteoglossids before the continental breakup was complete. Genetic studies have confirmed this hypothesis, showing that their 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 Scleropages species shows that little evolutionary change has taken place recently for these ancient fish.[6]

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, although later this species was placed in Scleropages with the name S. formosus.[7]

Several distinct, naturally occurring colour varieties are recognised, each found in a specific geographic region. They include the following:

In 2003, a study[2] was published which proposed breaking S. formosus into four separate species. This classification was based on both morphology and genetics, and includes the following species: