Arowana

Osteoglossinae are a subfamily of freshwater bony fish, commonly known as arowanas or bonytongues (though the latter is also used for other osteoglossiform fish). 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. In this family of fish, the head is bony and the elongated body is covered by large, heavy scales, with a mosaic pattern of canals. The dorsal and anal fins have soft rays and have long fin origins, while the pectoral and ventral fins have stiffer, longer rays. Arowanas are facultative air breathers and can obtain oxygen by ingesting air into its swim bladder, which is lined with capillaries like lung tissue. Despite this, they are not considered amphibious. The two genera each inhabit a different continent despite its members being freshwater fish, which suggests vicariance from the breakup of Gondwana.