By Hektor Jorgo
The Red Jardini arowana (Scleropages jardinii) is one of the most striking freshwater fish in the trade — a sleek, large-finned predator with reflective scales and red-tinted fins. It's also one of the clearest examples of a fish whose sale size and adult size are almost unrelated numbers, and planning for the second number is the entire point of this guide.
Appearance and Natural Range
Jardini arowana have an elongated, torpedo-shaped body, a large mouth set for surface and mid-water feeding, and long, flowing anal and dorsal fins that extend much of the length of the body. The "Red Jardini" designation describes a color morph with more pronounced red/orange tones in the fins and body, generally associated with populations from New Guinea, as distinct from the more silver-toned "Pearl Arowana" morph often linked to Australian populations. The species (Scleropages jardinii) is native to river systems in northern Australia and New Guinea.
Tank Requirements
Tank Size
250+ gallons, with a tank length of 6 feet or more, is the realistic target for an adult Red Jardini. This isn't just about water volume — arowana are strong, fast swimmers that need a long enough tank to turn around without difficulty, and a tank that's "big" by typical community-tank standards (say, the 55-gallon tank sometimes discussed for discus) is dramatically undersized for an adult arowana.
Aquascaping
Open swimming space is the priority — dense planting or heavy decor competes with the space an arowana needs to move. A secure, well-fitted lid is essential: arowana are well-known jumpers, particularly when startled, and can injure themselves on an open or poorly-secured tank top. Floating plants or dim lighting can help reduce startle responses for a fish that spends much of its time near the surface.
Water Parameters
| Parameter | Target Range |
|---|---|
| Temperature | 75-86°F (24-30°C) — see our arowana water temperature guide |
| pH | 6.5-7.5 |
| Ammonia / Nitrite | 0 ppm |
| Nitrate | <20 ppm |
| Water hardness | Soft to moderately hard |
Given the size of tank required, filtration and heating need to be sized for hundreds of gallons, not scaled up casually from smaller-tank equipment — this is a meaningfully different equipment budget than most freshwater setups.
Diet and Feeding
Red Jardini arowana are carnivores with a substantial appetite that grows alongside the fish:
- Juveniles: smaller meaty foods, appropriately-sized pellets formulated for carnivorous fish
- Adults: large carnivore pellets, and whole prey items (where appropriate and from safe sources) become part of the diet for many keepers
As with other large, fast-growing fish, waste output scales with size — the bioload principles discussed in our pleco waste guide apply here in an amplified form, and filtration needs to be planned for an adult-sized, carnivorous fish's output, not a juvenile's.
Tank Mates and Compatibility
Arowana are generally not aggressive toward similarly-sized tank mates in the sense of deliberately attacking them, but they are predatory toward anything small enough to be viewed as food — which, for an adult arowana, includes most typical community fish.
Appropriate tank mates are large, robust species that can share the substantial space an arowana setup requires without being at risk of becoming a meal. Large, hardy catfish are sometimes discussed in this context — species like Colombian shark catfish, which themselves need significant space (75+ gallons, groups of 3+) — though any such pairing only works if the tank is large enough to genuinely accommodate both species' adult needs, which in practice points back to the 250+ gallon range rather than a smaller "compromise" tank.
Red Jardini vs. Other Arowana Varieties
"Arowana" covers several distinct species and color morphs in the trade, and names can be applied inconsistently between sellers — a pattern that comes up repeatedly in this hobby, as discussed for stingray plecos and "Asian banjo catfish". For Jardini arowana specifically:
- Scleropages jardinii is the species — native to northern Australia and New Guinea
- "Red Jardini" generally describes individuals/populations with more red/orange in the fins and body
- "Pearl Arowana" is a commonly used name for more silver-toned Jardini, often associated with Australian-origin stock
The care requirements (tank size, water parameters, diet, jumping risk) are broadly the same across these color-morph distinctions — the morph affects appearance, not the fundamental space and care commitment.
Common Health Issues
- Injury from jumping/lid impacts — a recurring issue for arowana given their jumping tendency, especially in tanks without secure lids
- Stunting from inadequate tank size — keeping an arowana in too small a tank for extended periods can affect growth and long-term health, separate from any single water quality issue
- General water quality sensitivity scaled to the fish's size — given the large bioload, lapses in filtration or maintenance have an outsized effect compared to smaller fish
Quick Setup Checklist
- Tank: 250+ gallons, 6+ feet in length, for an adult
- Secure, well-fitted lid — arowana are strong jumpers
- Open swimming space, minimal dense decor
- Water temperature 75-86°F — see our arowana water temperature guide
- Diet: carnivore pellets scaled to size, whole prey items for adults
- Filtration and heating sized for hundreds of gallons, not scaled up from a smaller tank
- Tank mates: large, robust species only — no small community fish long-term
- Plan for a 10-20+ year commitment before acquiring
