Black Arowana Care Guide - Aquarium Size, Diet & Breeding

The Black Arowana is a long-bodied surface predator with large metallic scales, an upturned mouth and two prominent barbels on the lower jaw. Its elongated dorsal and anal fins run far back along the body, giving it the powerful, streamlined profile typical of the Osteoglossum genus.

Young Black Arowanas are particularly striking, often showing dark brown to almost black coloration with contrasting yellow, orange or reddish fin markings. As they mature, the body generally becomes lighter and more silvery or greenish, while the dark juvenile pattern gradually fades.

This species is an accomplished predator that spends much of its time close to the water’s surface. It can launch itself from the water to seize insects, small animals and other prey above the surface, a behaviour reflected in its flexible body and strongly upward-facing mouth.

In the wild, Black Arowanas inhabit warm, soft, acidic blackwater environments shaped by flooded forest and seasonal changes in water level. They are powerful, intelligent fish with a strong individual presence, but their eventual size and predatory nature make them specialist aquarium animals rather than typical community fish.

The Black Arowana is native to the Rio Negro basin in northern Brazil, South America. It is associated with blackwater tributaries, flooded forests and seasonally inundated habitats around the Negro River system.

A Black Arowana needs a specialised, very large aquarium of at least 1,500 litres for a single adult, although a substantially larger system is preferable for long-term housing. The tank should be at least 300 cm long, around 100 cm wide and 75 cm deep, with a completely secure, reinforced cover because this species is an exceptional jumper. Use powerful, reliable filtration with gentle to moderate circulation, leaving a broad open swimming area. Keep decoration sparse and stable, with smooth substrate, subdued lighting, driftwood and hardy plants positioned around the margins so the surface remains unobstructed.

Up to about 90 cm (35.4 in) in total length. Females are often slightly larger and deeper-bodied than males, although individual size varies and exceptional reports may differ.

Black Arowanas are carnivorous surface feeders. Offer a varied diet based on high-quality carnivore pellets, appropriately sized prawns, insects, earthworms, mussel and other marine or freshwater invertebrates. Whole fish should not be the regular staple because feeder fish can introduce disease and provide an imbalanced diet. Juveniles need suitably small portions, while adults should receive controlled meals to avoid obesity and water-quality problems.

Black Arowanas are best treated as solitary predators. In a suitably enormous aquarium, possible companions include robust, similarly sized South American fish such as large stingrays, datnoids or peaceful large catfish, provided every fish has enough territory and none can fit into the arowana’s mouth. Smaller fish, delicate species, fin-nippers and boisterous tankmates are unsuitable because they may be eaten, injured or outcompeted. Adult arowanas can also become territorial toward their own kind and other surface-dwelling fish.

Black Arowanas are mouthbrooders and are difficult to breed in home aquariums because they require exceptional space, mature adults and carefully managed water quality. After spawning, the male carries the eggs and developing fry in his mouth for several weeks, releasing the young periodically before taking them back when threatened. Breeding is more commonly achieved in very large indoor systems or ponds than in ordinary aquariums.

Sex differences are subtle, especially in young fish. Mature females are generally larger and deeper-bodied, while males may appear slightly more streamlined and are the sex that carries the eggs and fry during mouthbrooding; these traits are not always reliable without observing breeding behaviour.