Osteoglossum is a genus of large, primitive bony-tongue fish (family Osteoglossidae) native to the Amazon and Orinoco basins of South America, found across Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, and Venezuela. Its two species - the silver arowana, O. bicirrhosum, and the black arowana, O. ferreirai - are elongated, laterally compressed surface predators with a large upturned mouth, prominent barbels on the lower jaw, and a metallic sheen to their scales; among the largest fish in the atlas, they grow from roughly 90 up to 47 in.
Arowanas are ambush surface hunters, striking upward at insects, small fish, and other prey near the water's surface, and are well known for their powerful jumping ability - aquarium and pond setups housing them need secure, heavy covers. Both species are mouthbrooders: the male carries the fertilised eggs and, later, the free-swimming fry in his mouth for protection over several weeks, an unusual and closely watched behaviour among aquarists who keep them. The silver arowana in particular is a long-established, if demanding, fixture in large specialist aquariums and ponds, prized for its size, movement, and dragon-like appearance; given its adult size, it requires a very large tank or pond long-term. Conservation status is mixed - one species is Least Concern, the other not yet formally evaluated.