Arowanas , also known as aruanas or arawanas or “bonytongues” or “dragon fish”, are magnificent freshwater bony fish of the family Osteoglossidae. Arowanas typically grow to around 3 to 4 feet in captivity.  There are six known species of arowana, distributed across Asia, Australia, Africa and South America. The ones commonly found in local aquarium outlets are juveniles or young adults belonging to the silver, red and gold varieties of the species. 

The head is bony and its 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 fish can obtain oxygen from air by sucking it into the swim bladder, which is lined with capillaries like lung tissue. The arapaima is an “obligatory air breather”.

Arowanas grow very quickly, but the gender differences are indiscernible during their juvenile stage and become apparent only when the fish are more mature at around four years of age, measuring about 17 to 23 inches.  Males usually have a shallower body depth, bigger head and mouth, a longer anal fin,  more intensely coloured than the females, and exhibit more aggressions in competing for food.  The females tend to have slightly larger and broader body shape, and in particular during the mating season.

Several of this species of osteoglossid exhibit extensive parental care. Arowana builds nests and protect the young after they hatch. Some of them are mouthbrooders, where the parents hold hundreds of eggs in their mouths.  Arowana fry usually stay in the parent’s mouth for a period of one to two weeks, or until their yolk sacs disappear. The fry may then make several tentative trips outside the parent’s mouth to investigate the surroundings before leaving permanently.   The juvenile fry needs extra care as they are particulary fragile during this stage of their lives.

Osteoglossids are carnivorous, often being specialized surface feeders. It can glides through water with elegance and least effort, capable of moving with power and lightning speed. They are also excellent jumpers and has been reported that Osteoglossum species seen leaping more than 6 feet (approximately 2 metres) above the water surface to pick off insects and birds from overhanging branches in South America.  There are rumours that they can capture prey as large as low flying bats and small birds.  It is commonly known that the adult fish will eat practically anything that can fit into its mouth.  Young arowanas can be fed food like brine shrimp or bloodworms.  Arowana prefers live food, however it will also accept frozen or processed food with a balanced suitable diet consisting of crickets, centipedes, small frogs, freshwater prawns and the small fish such as guppies, supplements like vitamin—enriched krill, and pellet and flake food and so on.

Arowanas will merge in groups of five to eight and any fewer may exhibit signs of dominance and aggression. They are compatible with other semi-aggressive fish that cannot fit in the its mouth.

Culture wise, Arowanas are often used for feng shui to bring good luck in the eyes of the Chinese.  They have appearance and majesty of the Chinese Dragon, which a is a symbol of good luck and prosperity.