Silver Arowana Care Guide - Aquarium Size, Diet & Breeding

The Silver Arowana is a spectacular surface-dwelling predator with an elongated, ribbon-like body, large metallic silver scales and long dorsal and anal fins that run along much of its back and underside. Its upturned mouth and two prominent barbels give it the common nickname “water monkey” in parts of its native range, reflecting its ability to seize prey from the surface and even launch out of the water.

Silver Arowanas are native to slow-moving rivers, floodplain lakes and seasonally flooded forests across northern and central South America. Their range includes the Amazon, Essequibo and Orinoco river systems in countries such as Brazil, Peru, Colombia, Guyana and French Guiana.

An adult Silver Arowana needs an enormous aquarium of at least 1,500 litres, with a practical footprint around 240 × 90 cm or larger; substantially bigger systems are preferable for fully grown specimens. The aquarium must have powerful, dependable filtration, strong oxygenation and a completely secure, reinforced lid because these fish are exceptional jumpers. Use open swimming space with subdued lighting, smooth sand or fine gravel, and only robust, securely anchored wood or plants around the margins so the fish cannot injure its long body or barbels.

Up to about 90 cm (35 in) in total length. Females may become slightly deeper-bodied and occasionally larger than males, although size varies with genetics, diet and growing conditions.

Silver Arowanas are carnivorous predators that naturally take fish, crustaceans, insects, frogs and other animals near the water surface. Offer a varied diet of high-quality carnivore pellets supplemented with appropriately sized prawns, mussels, earthworms and occasional whole fish from safe, disease-free sources. Avoid feeder goldfish and other nutritionally poor or parasite-prone feeder fish, as well as relying heavily on fatty meat such as beef heart.

Silver Arowanas are best kept alone, particularly in a standard home aquarium. Very large, robust tankmates such as mature datnoids, large knifefish, bichirs, stingrays or suitably sized large catfish may sometimes work in an exceptionally spacious system, but compatibility is never guaranteed. They will eat smaller fish, shrimp and other animals that fit in their mouths, and may injure slow, delicate or highly territorial companions.

Silver Arowanas are mouthbrooders and are rarely bred in home aquariums because they require very large facilities. A compatible adult pair may spawn after courtship, with the male collecting and incubating the eggs in his mouth for several weeks. The male releases the well-developed fry periodically, and the young may return to his mouth when threatened. Breeding groups should be managed by experienced keepers, as adults can become aggressive and spawning fish need exceptional space.

Sexes are difficult to distinguish in young Silver Arowanas. Mature females are often deeper-bodied, while males may have a somewhat longer anal fin and a larger, broader mouth associated with mouthbrooding; these differences are not completely reliable outside breeding condition.