arowana

Arowanas are freshwater bony fish of the family Osteoglossidae, also known as bonytongues.^[1] 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 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 arowana is a facultative air breather and can obtain oxygen from air by sucking it into its swim bladder, which is lined with capillaries like lung tissue.^[2]