Arowanas are large surface-oriented fish that need specialist adult accommodation and a secure cover. A small juvenile is not a low-cost route to a normal community aquarium. Identify the species and have its lifelong setup ready before buying.
Which arowana are you considering?
Silver arowana, Osteoglossum bicirrhosum: a very large South American predator. Seriously Fish lists about 80 cm standard length, excluding the tail, and restricts its recommendation to public installations or the largest private aquaria. Plan for substantial adult length and turning room, not a promised small “aquarium size.”
Black arowana, O. ferreirai: another large South American species. Dark juveniles change appearance as they grow. It is not a smaller substitute that removes the need for a specialist aquarium.
Asian arowana, Scleropages formosus: an Asian species with ornamental red, gold and other trade forms. Color names and prices do not establish species, legal provenance or the eventual quality of an individual. Check its documentation before purchase.
Australian arowanas: S. jardinii and S. leichardti require species-specific planning. Fishes of Australia records jardinii reaching 100 cm total length, commonly around 55 cm, and describes solitary territorial behavior. Do not treat it as a guaranteed 24-inch, peaceful community fish.
African arowana, Heterotis niloticus: a different bonytongue with its own size and feeding needs, not a fish to maintain using a generic silver-arowana predator recipe. Arapaima or pirarucu are also different giant fishes, not arowana varieties suitable for a home display.
Adult space and a secure aquarium
There is no universal 180- or 240-gallon adult answer. Species, final body size, aquarium width and unobstructed surface swimming space determine suitability. A long narrow tank can hold a large volume and still prevent comfortable turning. For silver arowanas, think in terms of a custom installation rather than a standard large community tank.
Arowanas jump. Secure the cover and every access gap, protect exposed equipment and avoid sharp overhead obstacles. Floating plants or dimmer lighting do not replace a lid. Leave room for safe feeding, cleaning and eventual fish transport; do not assume a shop or public aquarium will accept an outgrown adult.
Water quality and filtration
Use the identified species and source stock to set temperature and chemistry. For many aquarium silver arowanas, a stable tropical temperature in the mid-20s Celsius and appropriately soft to moderately mineralized water are practical conditions. Do not apply one pH range to every species or make rapid changes to chase a target.
Complete the nitrogen cycle first. Maintain zero ammonia and nitrite, effective biological filtration and good oxygenation. Monitor nitrate and remove accumulated waste through regular partial water changes. Surface breathing or hardiness does not excuse low oxygen or polluted water.
Feeding
For predatory Osteoglossum and Scleropages, use an accepted, appropriately sized complete food for carnivorous fish with varied suitable aquatic foods or insects. Confirm that a newly bought fish eats and swallows comfortably. Youngsters may need smaller, more frequent portions than adults.
Live feeder goldfish, rosy reds or guppies are unnecessary as a foundation and may introduce infections. Neither seafood alone nor one insect species guarantees a balanced diet. Avoid mammal and poultry meat as staples, remove leftovers and adjust quantity to condition rather than forcing rapid growth.
Companions and breeding
Small fish may be swallowed; larger fish may still be harassed or attack the arowana. Different arowana species also vary markedly in aggression. Raising several juveniles together or feeding heavily does not guarantee harmony as adults.
Do not add giant catfish, pacu or other oversized fish as convenient companions: their own adult accommodation may exceed the arowana’s. Review the arowana compatibility guide and maintain an established separation option.
Breeding is a specialist project. Christopher Brown’s University of Hawaii silver-arowana culture account describes a large covered aquaculture setup. Mouthbrooding and parental sex differ by species, and external sexing is unreliable. Do not remove a divider after a fixed month and assume two adults are safe together. Yolk-sac young need specialist protection and suitable feeding as they develop.
Asian arowana documentation
Scleropages formosus is listed in CITES Appendix I. Singapore’s Animal and Veterinary Service explains its registered-farm and export-permit requirements. Farm registration does not by itself authorize ownership or import everywhere.
For the United States, Endangered Species Act requirements are separate from CITES paperwork; a seller’s “captive-bred” certificate alone is not authorization. Check the U.S. Fish and Wildlife Service’s permit guidance and the applicable local rules before arranging a transaction. Other arowana species can also face local restrictions.
