In contrast, arapaima have been introduced to several tropical regions outside the native range (within South America and elsewhere), where they are sometimes considered invasive species.

[5] Its Portuguese name, pirarucu, derives from the Tupi language words pira and urucum, meaning "red fish".

[3][7][8] As a consequence of this taxonomic confusion, most earlier studies were done using the name A. gigas, but this species is only known from old museum specimens and the exact native range is unclear.

[7][8][9][11][12] These fish are widely dispersed and do not migrate, which leads scientists to suppose that more species are waiting to be discovered in the depths of the Amazon Basin harbors.

Anecdotal reports suggest that specimens as long as 4.57 m (15 ft 0 in) exist, but verification is deemed impossible, and thus considered questionable.

In addition to gills, it has a modified and enlarged swim bladder, composed of lung-like tissue, which enables it to extract oxygen from the air.

[17] The diet of the arapaima consists of fish, crustaceans, fruits, seeds, insects, and small land animals that walk near the shore.

The arapaima male is a mouthbrooder, like the related Osteoglossum genus, meaning the young are protected in his mouth until they are older.

[21] Museum specimens are found in France, England, the United States, Brazil, Guyana, Ecuador and Perú.

Designers have begun using the skin of the arapaima as leather to make jackets, shoes, and handbags, and to cover furniture.

The "Kenyir monster", or "dragon fish" as the locals call it, was claimed to be responsible for the mysterious drowning of two men on 17 June.

In 2013, Whole Foods began selling farm-raised arapaima in the United States as a cheaper alternative to halibut or Chilean sea bass.

[30] As efforts at restricting catches were largely unsuccessful, arapaima fishing was banned outright in Brazil in 1996, due to declining populations.

Since 1999, both subsistence and commercial fishing have been permitted in specially designated areas under a sophisticated sustainable management strategy.

This approach has led to massive recovery of once-depleted stocks; in a sampling of 10 areas conducted using traditional counting methods, the population was found to have grown from 2,500 in 1999 to over 170,000 in 2017.