Arowana

Arowana

Subfamily Heterotidinae
Arapaima
Heterotis
Subfamily Osteoglossinae
Osteoglossum
†Phareodus
Scleropages

Arowanas are freshwater bony fish of the family Osteoglossidae, also known as bonytongues. In this family of fish, 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 "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 the swim bladder, which is lined with capillaries like lung tissue.