Arowanas are freshwater bony fish of the subfamily Osteoglossinae, also known as bony tongues (the latter name is now often reserved for Arapaiminae). 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.

Asian arowanas are considered to be symbols of good luck and prosperity, especially by those from Asian cultures. This reputation derives from the species’ resemblance to the Chinese dragon, considered an auspicious symbol. The large metallic scales and double barbels are features shared by the Chinese dragon, and the large pectoral fins are said to make the fish resemble “a dragon in full flight.”

In addition, positive feng shui associations with water and the colors red and gold make these fishes popular for aquaria. One belief is that while water is a place where chi gathers, it is naturally a source of yin energy and must contain an “auspicious” fish such as an arowana to have balancing yang energy. Another is that a fish can preserve its owner from death by dying itself.