Arapaima Care Guide - Size, Habitat, Diet & Breeding

Arapaima gigas is one of the world’s largest freshwater fishes and is renowned for its immense size, armour-like scales and ability to breathe atmospheric air. Its elongated body is usually olive-green or grey toward the front, becoming darker and often reddish near the tail, especially in mature individuals. The large, upturned mouth reflects its life as a powerful surface predator.

Despite its bulk, the Arapaima is capable of sudden bursts of speed. It commonly rises to the surface to gulp air using a highly modified, lung-like swim bladder, an adaptation that allows it to survive in warm, oxygen-poor waters. These dramatic surface visits are one of its most distinctive behaviours.

In nature, Arapaima inhabit quiet channels, oxbow lakes, flooded forests and seasonally inundated plains. They hunt fish and other sizeable prey, often ambushing them from below or striking prey near the water’s surface. Their heavily scaled bodies provide protection from predators and help them navigate dense, changing floodplain environments.

Arapaima are generally solitary or found in temporary family groups rather than permanent shoals. They are important food fish throughout their native range, but wild populations have been affected by intense fishing pressure and habitat changes. Their extraordinary adult size makes them a species for major public aquariums and specialist institutions, not a conventional home-aquarium fish.

Arapaima gigas is native to slow-moving rivers, floodplain lakes and wetlands of the Amazon Basin in South America, particularly across Brazil and neighbouring parts of Peru, Colombia and Bolivia. Its range is associated with warm, seasonally flooded freshwater habitats.

There is no realistic standard home-aquarium setup for an adult Arapaima. A suitable facility requires a purpose-built aquatic exhibit of many thousands of litres, with substantial swimming length, width and depth; a long tank or pool measuring at least several metres in each major dimension is a more appropriate guideline than a conventional aquarium volume. Strong filtration, excellent oxygenation, secure construction and generous open swimming space are essential, along with smooth substrates, sturdy structures and subdued areas resembling flooded forest or slow-moving river habitat. Open access to the water surface is crucial because the fish must breathe atmospheric air.

Up to about 300 cm (118 in) in exceptional cases; females are generally larger and heavier than males, while many captive adults remain closer to 150–250 cm (59–98 in).

Arapaima are carnivorous predators that feed mainly on fish, crustaceans and other aquatic animals. Captive specimens may accept appropriately sized whole fish and carefully prepared meaty foods, with a varied diet chosen to avoid nutritional deficiencies. Food must be proportionate to the fish’s size, and uneaten portions should be removed promptly to protect water quality.

Arapaima are best maintained alone because they can swallow smaller fish and may injure or overpower tankmates. In enormous public or specialist facilities, only very large, robust fish with compatible water requirements could be considered, and even then careful monitoring is essential. Small community species, territorial fish and delicate tankmates are unsuitable, while competition for food and space can create serious problems.

Arapaima form pairs and breed during the rising-water season, constructing shallow nests in sandy or muddy areas. The female lays eggs in the nest, while both parents defend the territory and protect the young. After hatching, the fry remain close to the male, often gathering above his head, where parental care and protective secretions help improve their survival. Successful breeding requires an exceptionally large, carefully managed aquatic facility.

Females typically grow larger and deeper-bodied than males. Mature males may show stronger reddish coloration toward the tail during the breeding season, although colour can vary with age, condition and locality.