Jardini Arowana

The Jardini arowana (Scleropages jardinii), sold as Gulf saratoga, Australian bonytongue, pearl or Jardini arowana, is an osteoglossid bonytongue native to the still and slow-moving waters of northern Australia, southern New Guinea and Indonesia - streams, creeks, billabongs and swamps, usually in clear water with surface vegetation or overhanging branches. It is IUCN Least Concern and not CITES-listed, unlike the Asian arowana, which is why it is freely traded in most markets. Adults reach about 90-100 cm, live near the surface, and are solitary and territorial by nature.

Wild fish reach up to 100 cm standard length, with 55 cm common and first maturity around 45 cm; Seriously Fish works from 90 cm and TankBud also gives about 90 cm, so plan for 90-100 cm. The profile's 35 cm describes a young adult, not the ceiling - growth is steady and the fish is sold far smaller than it gets. Size the enclosure for the adult from day of purchase, because a 35 cm fish in a 300 L tank has no upgrade path once growth stops.

Jardini are solitary and territorial: FishBase records them as solitary and territorial in the wild, and Seriously Fish describes most specimens as very territorial and belligerent towards other arowana - widely considered the most aggressive arowana under aquarium conditions. Keep it singly as the general rule; a group only works in a tank large enough for 6-10 adults so fighting is dispersed, which is beyond most setups. It hunts near the surface around structure, so a bare, brightly lit tank with nowhere to break line of sight stresses a territorial fish rather than calming it.

Plan for an adult near 90-100 cm in a tank of at least 180 x 60 cm (about 648 L) - Seriously Fish calls that the absolute bare minimum for an adult fish, TankBud asks for 1,200 L - fitted with a very heavy, tightly fitting cover, because this species is a known, powerful jumper and an open or loose top is how keepers lose them. Filtration must be strong and efficient with regular water changes strictly observed, since prolonged sub-standard conditions cause eye and gill problems. Leave the surface lane open: it is a surface hunter that also gulps air, so the cover must be tight against jumps while the water surface stays reachable.

Read the minimum as floor area first: 180 x 60 cm of usable base - a long, wide box rather than a tall column - because volume alone can be met by a narrow tank that gives a 90-100 cm fish no room to turn. Seriously Fish is explicit that this species requires a lot of swimming space and that decor is not critical, so keep hardscape light and leave the length open as a surface lane. A 300 L tank cannot reach the published footprint at any height, whatever its litre count suggests.

Carnivorous surface feeder: offer earthworms, gut-loaded mealworms, waxworms and frozen or dried bloodworm, prawn, mussel and pellets, varied so the fish does not fixate on one food. There is no real benefit to live feeder fish - only the risk of introducing disease or parasites. Feed small amounts several times a day while the fish is under about 30 cm, then a single feeding per day above that, and remove uneaten food after each feeding to protect water quality.

Community use is possible but never guaranteed: it eats smaller fish, and while some individuals tolerate large catfish, characins, cyprinids, knifefish and robust cichlids, others will not tolerate any tankmate whatsoever. Add the arowana last and reassess as it grows, because appetite scales with size. Anything swallowable is food and invertebrates are prey, not cleanup crew - in practice most keepers run this species single.

Verdict: an advanced specialist fish - a 90-100 cm, highly aggressive surface predator that needs at least 180 x 60 cm (about 648 L, preferably 1,200 L), strong filtration, strictly kept-up water changes and a heavy lid that stays shut. Skip it if you want a reliable community tank, if you cannot secure the top, or if 300 L is your ceiling: the published minimum is already double that and this is documented as the most aggressive arowana in aquaria. It is legal and unprotected (IUCN Least Concern, not CITES-listed), which makes availability easy and the responsibility entirely yours.