Arowana Care Guide: Tank Size, Diet, Water Parameters and Temperament
Arowanas are stunning, long-lived predators, but they're also one of the biggest commitments in the freshwater hobby - a single adult can need a 250-gallon (946 L) tank, a reinforced floor, and a decade or more of dedicated care. This guide covers legal species, realistic tank sizing, water chemistry, diet, temperament, and the setup details that determine whether an arowana thrives or outgrows its home within a year.
What Is an Arowana?
Arowanas belong to the family Osteoglossidae, nicknamed "bony tongues" or "dragon fish" for their large scales and upturned mouths built for snatching prey at the surface. The species commonly and legally available in the US trade include:
- Silver arowana (Osteoglossum bicirrhosum) - the most widely kept, native to the Amazon basin.
- Jardini/Australian (pearl) arowana (Scleropages jardinii) - native to northern Australia, slightly smaller and often considered a bit hardier.
- Black arowana - a South American relative with darker juvenile coloration that fades with age.
- Red-tailed golden/red arowana forms - marketed under various names; some of these color forms are genetically tied to the restricted Asian arowana complex, so species verification matters before you buy (more on this below).
Size and Lifespan
Growth is fast and easy to underestimate. Silver arowanas commonly reach 3 feet (91 cm) as adults, with some individuals approaching 4 feet (122 cm). Jardini arowanas top out smaller, around 24 inches (61 cm). Expect a typical lifespan of 10-15 years, with well-kept individuals living 20+ years - this is a fish you plan a room around, not just a tank.
Juveniles grow quickly enough to outgrow a starter tank within their first year, which is the single most common planning mistake new keepers make.
Tank Size: Footprint Matters More Than Depth
The consensus minimum for a single adult silver arowana is 250 gallons (946 L), with a footprint of at least 6-8 feet long by 2-3 feet wide (183-244 cm by 61-91 cm). Jardini and other smaller species can be housed in 180-200+ gallons (681-757 L).
Tank size recommendations vary widely across sources - anywhere from 150 to 300+ gallons - largely because some are describing a bare-minimum juvenile setup and others a proper adult, long-term home. A 55-125 gallon (208-473 L) tank works only as a short-term stopgap for a young fish and should not be treated as an end-state size.
The reason footprint outranks depth: arowanas swim laterally, not vertically. A tank that's tall but narrow forces the fish to turn in cramped space, which can contribute to spinal deformities and stress. A long, shallow tank gives it a straight lane to cruise.
| Life stage / species | Minimum tank size | Footprint |
|---|---|---|
| Juvenile silver arowana (short-term) | 55-125 gal (208-473 L) | Stopgap only |
| Adult silver arowana | 250+ gal (946+ L) | 6-8 ft x 2-3 ft (183-244 x 61-91 cm) |
| Adult jardini arowana | 180-200+ gal (681-757 L) | Long, shallow |
| Arapaima (related giant fish, for comparison) | 1,000+ gal (3,785+ L) | Public-aquarium scale |
Water Parameters
| Parameter | Target range |
|---|---|
| Temperature | 75-85°F (24-29°C) |
| pH | 6.0-7.5, aim for 6.5-7.0 |
| General hardness | Soft to moderate, roughly 1-8 dGH |
| Ammonia / nitrite | 0 ppm |
| Nitrate | Kept low with large, frequent water changes |
| Water change schedule | 30-50% weekly |
Published pH ranges vary (some cite 5.0-7.5, others a tighter 6.5-7.5), largely because arowanas tolerate a fairly broad range once acclimated. The real risk isn't the exact number - it's a sudden swing. Aim for the 6.5-7.0 middle ground and prioritize stability over chasing a precise figure.
Because a large, meat-eating fish produces a heavy bioload, weekly water changes aren't optional - they're the main lever for keeping nitrate down between deep-cleaning cycles.
Filtration and Tank Setup
Oversized canister or sump-style filtration is mandatory. Arowanas are messy eaters producing a high bioload, so turnover well above the standard "4x tank volume per hour" guideline is warranted. Since they feed at the surface, gentle surface flow is preferable to strong turbulence that pushes food around before the fish can grab it.
Keep the aquascape sparse:
- Substrate: gravel or sand.
- Decor: minimal, sturdy driftwood or rock - avoid anything sharp, since a startled arowana can dart into decor at speed and injure itself.
- Plants: floating or tall plants for a sense of security, rather than dense planting that eats into swimming room.
- Open water column: the priority is a clear lane for the fish to cruise, not a heavily furnished display.
You can browse arowanas and other large predatory species in FishyHub's Monster Fishes category, and outfit the system with appropriately sized equipment from the Filters category.
Lid and Jump Security
A heavy, weighted or locking canopy is non-negotiable. Arowanas are among the strongest jumpers in the hobby - the behavior is a wild adaptation for snatching insects and small prey above the waterline, and in captivity it becomes a genuine safety hazard. An unsecured lid can be cracked or launched clean off by a startled adult. Keep the water level a few inches below the rim and eliminate any gaps around cords, filter intakes, or canopy seams.
Diet
Arowanas are carnivorous with large appetites. A balanced approach combines:
- Floating pellets (40%+ protein) as the dietary base, since they're formulated for complete nutrition and easy to store.
- Meaty proteins: shrimp, krill, earthworms, crickets, silversides, and beef heart in moderation.
Feed at or near the surface, since arowanas are top-feeders by nature. Feeding frequency:
- Juveniles: 2-3 times daily.
- Adults: every 1-2 days, adjusting to body condition - avoid daily feeding for adults, since it adds unnecessary waste load on top of an already heavy bioload. Some sources stretch adult feeding to every 2-3 days, so use body condition rather than the calendar as your guide.
Feed only what's cleared within a couple of minutes to limit waste buildup.
On live feeder fish: sources disagree here. Some list feeders as a normal dietary component; others warn against them outright. The safer approach is to treat pellets and varied meaty proteins as the base diet and use live feeders only occasionally, sourced from a quarantined, disease-free supply - a live-feeder-only diet raises parasite and disease risk and can leave nutritional gaps.
If you're raising a juvenile, it's considerably easier to establish pellet acceptance early than to convert an adult that's become dependent on live food later.
Temperament and Tankmates
Arowanas are solitary, territorial, and highly predatory. As a rule of thumb, anything small enough to fit in an arowana's mouth will eventually become food. Suitable tankmates are large, robust, fast-moving, or armored species in a suitably sized tank:
- Large plecos and catfish
- Big cichlids (oscars, jaguar cichlids)
- Freshwater stingrays
- Datnoids
- Pacus
- Knifefish
- Giant gouramis
- Tinfoil barbs
Avoid housing two arowanas together unless the tank is exceptionally large - conspecific aggression between arowanas is common and can result in injury.
How Arowanas Compare to Other Giant Freshwater Fish
Arowana often shows up alongside other "monster fish" like oscars, pacus, and freshwater stingrays in exotic predatory-fish discussions. Among giant primitive fish specifically, arowana sits at the more accessible end: arapaima, a relative in the same broad group of large primitive fishes, needs 1,000+ gallons and is realistically a public-aquarium species rather than a home-hobby option. An arowana is a serious commitment, but arapaima is on another scale entirely.
Types and Color Forms - and the Asian Arowana Legal Issue
Beyond silver and jardini, hobbyists will encounter color-form terminology like red, golden, and black arowana. Here's the critical caveat: some marketed "red" or "golden" forms are actually the regulated Asian arowana (Scleropages formosus and related color forms), not a legal domestic variety.
The Asian arowana is CITES-listed and illegal to own in the US. Its rarity and cultural "luck" symbolism have historically pushed black-market prices into the tens of thousands of dollars - this is a legal red flag, not an aspirational purchase. Before buying any arowana marketed with an unfamiliar color-form name, confirm the species and, where relevant, ask for documentation - a legitimate seller of legal species should be able to identify the exact species being sold. Legal, commonly available species in the US trade are silver, jardini, and black arowana; always verify state law as well, since regulations can vary.
Tank Stand, Structural Load, and Glass vs. Acrylic
A filled 250-gallon system can weigh 2,500+ pounds once you account for water (roughly 8.3 lb per gallon), substrate, decor, and the tank/stand itself. This is a genuine structural consideration, not a decor footnote:
- Use a stand rated well above the tank's dry weight - steel-frame or built-in stands are commonly recommended over standard wood furniture-style stands at this scale.
- In many homes, a tank this size requires floor joist reinforcement or placement on a ground-floor slab. If you're unsure, consult a structural professional before filling a large system.
You can compare tank options in the Tanks & Stands category when planning a build this size.
Glass vs. acrylic is also worth weighing at this scale:
| Material | Pros | Cons |
|---|---|---|
| Glass | Cheaper at scale, highly scratch-resistant | Heavier, more prone to stress cracks under impact |
| Acrylic | Lighter, more impact-resistant (relevant given jumping risk) | Scratches more easily, higher cost |
Breeding
Arowana breeding is technically possible but impractical for most home aquarists. They are mouthbrooders - the male incubates eggs and fry in his mouth for roughly 1-2 months - and spawn seasonally, producing relatively few but large offspring. Successful breeding generally requires very large, mature setups and is essentially limited to specialized or commercial breeders rather than hobby tanks.
Health and Common Mistakes
Watch for:
- Drop-eye: the eye rotates downward, largely caused by chronic downward feeding or staring at the substrate. Prevent it by feeding consistently at the surface.
- Dropsy and bacterial infections: linked to poor water quality.
- Physical injuries: from sharp decor or jump-related incidents.
Common mistakes to avoid:
- Buying a juvenile for a small tank without planning for its growth curve, leading to stunted development or forced rehoming.
- Skimping on the lid, resulting in jump-outs or shattered canopies.
- Feeding from the bottom long-term, contributing to drop-eye.
- Underestimating bioload and running underpowered filtration, causing ammonia or nitrite spikes.
- Adding small tankmates that simply become food.
- Ignoring floor-load requirements for a large filled tank.
- Relying solely on feeder fish, which raises disease risk and can create nutritional gaps.
The Real Cost of Ownership
Most discussions of arowana cost focus only on the fish itself. The bigger expense is the system: a 250+ gallon tank, a rated stand, oversized filtration, a secure canopy, heating, and the electricity to run it all continuously, plus ongoing food costs for a large daily or near-daily eater. Budget for the full setup, not just the livestock price tag, before committing.
Ready to plan your setup? Browse arowanas and other large predatory species in FishyHub's Monster Fishes category to see what's currently available.
Frequently Asked Questions
What size tank does an arowana actually need?
An adult silver arowana needs 250+ gallons (946+ L) with a long, shallow footprint of at least 6-8 feet. Jardini and smaller species can work in 180+ gallons (681+ L), but depth should never substitute for length - lateral swimming room is what matters most.
Can I keep an arowana with other fish?
Yes, but only large, robust, or armored species in a tank big enough for everyone - think big cichlids, large plecos, freshwater stingrays, or pacus. Avoid any tankmate small enough to fit in the arowana's mouth, since it will eventually be eaten.
Why do arowanas jump out of tanks?
Jumping is a natural adaptation for snatching insects and prey above the waterline in the wild. In captivity, that same instinct makes an unsecured tank dangerous, so a heavy, weighted, gap-free lid is essential.
Are all arowanas legal in the US?
No. The Asian arowana and its regulated color forms are CITES-listed and illegal to own in the US, while silver and jardini arowanas are legal and commonly sold. Some marketed "red" or "golden" forms may actually be Asian arowana crosses, so verify the species before buying.
What do arowanas eat?
A base of high-protein floating pellets (40%+ protein) supplemented with meaty proteins like shrimp, krill, and earthworms. Feed at the surface, since arowanas are natural top-feeders, and treat live feeder fish as an occasional, carefully sourced treat rather than a dietary staple.
How long do arowanas live and how big do they get?
Typically 10-15 years, with some individuals reaching 20+ years in captivity. Adult size ranges from about 2 feet (jardini) to 3-4 feet (silver arowana), depending on species.
Can arowanas breed in a home aquarium?
Technically, yes, but it's impractical for most hobbyists. Arowanas are mouthbrooders requiring very large, mature setups and seasonal spawning conditions, which is why breeding is mostly limited to specialized or commercial breeders.
