What the Australian Arowana Is and Why It Matters

The Australian arowana (Scleropages jardinii) is a large, silver-scaled freshwater fish native to northern Australia and southern New Guinea. It grows to about 24 inches in the aquarium, though wild specimens can reach 30 inches. Unlike its Asian cousins, the Australian arowana is legal to own in most countries without special permits, making it the accessible choice for hobbyists who want an arowana but cannot navigate the restrictions on endangered species.

This fish is a surface feeder and ambush predator. It hunts by waiting near the water's surface, then striking at prey with explosive speed. In the wild, Australian arowanas live in slow-moving rivers, floodplain swamps, and billabongs where water is often stained dark by tannins and vegetation. Understanding this behaviour and habitat is the foundation for keeping one alive and healthy in captivity.

Key Takeaways

  • Australian arowanas need a tank of at least 150 gallons, with 180 gallons or more preferred, because they are active swimmers that grow large and live 15 to 20 years.
  • They are carnivorous surface feeders that eat live or frozen fish, shrimp, and insects; feeding live goldfish or feeder fish can introduce parasites and disease.
  • Water temperature should stay between 74 and 82 degrees Fahrenheit, with a pH between 6.0 and 7.0, and they tolerate slightly acidic, tannin-stained water similar to their native habitat.
  • Australian arowanas are solitary and territorial; they will attack or kill other fish of similar size, though they can sometimes coexist with very large, fast-moving tankmates.
  • They are prone to jump, so a tight-fitting lid is essential, and they can develop eye problems if the tank lacks proper lighting or if food is offered only from one side.

Tank Size and Setup Requirements

A single Australian arowana requires a minimum of 150 gallons, though 180 to 250 gallons is more realistic for long-term health and natural behaviour. The tank should be longer than it is tall—a 6-foot by 2-foot by 2-foot setup works better than a tall, narrow one—because arowanas are horizontal swimmers that patrol the water column rather than explore vertical space. They also need room to turn and accelerate when striking at prey.

The substrate can be sand or fine gravel; arowanas do not dig, so the choice is mainly about maintenance and aesthetics. Driftwood and large rocks provide visual interest and create shadowed areas, but leave at least 60 percent of the tank open for swimming. Arowanas are not plant-eaters, but live plants are easily uprooted or damaged by their movement and feeding strikes, so most keepers skip them or use hardy, anchored species like Java fern.

Filtration must be strong but not create a current so powerful that the fish exhausts itself swimming against it. A canister filter rated for 200 to 300 gallons per hour works well for a 180-gallon tank. Water changes of 25 to 30 percent every two weeks keep nitrate levels down; arowanas are sensitive to poor water quality, and high nitrate causes eye problems and fin damage over time.

Water Conditions and Temperature Control

Australian arowanas thrive in warm, slightly acidic water. Keep the temperature between 74 and 82 degrees Fahrenheit; most keepers maintain 76 to 78 degrees as a stable middle ground. A reliable aquarium heater and thermometer are non-negotiable. Temperature swings stress the fish and make them susceptible to disease.

The pH should sit between 6.0 and 7.0. In the wild, Australian arowanas live in water stained by tannins from decaying vegetation, so they tolerate and often prefer slightly acidic conditions. Adding driftwood or Indian almond leaves lowers pH naturally and mimics their native environment. Test the water weekly when the tank is new, then monthly once it is established.

Lighting should be moderate—12 hours on, 12 hours off is a standard photoperiod. Arowanas do not require intense lighting, and excessive light can contribute to eye problems, especially if the fish is fed only from one side of the tank (which causes it to look in one direction repeatedly). Vary feeding positions to keep the fish's vision balanced.

Feeding and Diet

Australian arowanas are obligate carnivores. In captivity, they eat frozen or thawed fish (smelt, herring, capelin), frozen shrimp, and insects like crickets and grasshoppers. Many keepers also offer prepared pellets designed for large carnivorous fish, though arowanas often prefer live or frozen whole prey. Feed juveniles once or twice daily; adults do well on once-daily feeding or every other day, depending on size and activity level.

Avoid feeding live goldfish or feeder fish regularly. Live prey can carry parasites, bacteria, and viruses that infect the arowana. If you do use live food occasionally, source it from a reputable supplier and quarantine it first. Frozen prey is safer, cheaper, and just as nutritious. Thaw frozen food in tank water or a separate container before offering it.

Feed only what the fish will consume in a few minutes. Uneaten food decays and fouls the water. Arowanas are enthusiastic eaters and will beg at feeding time, but overfeeding leads to obesity, constipation, and poor water quality. A piece of fish or shrimp about the size of the fish's eye is a reasonable portion for an adult.

Temperament and Tankmate Compatibility

Australian arowanas are solitary, territorial fish. They will chase, bite, and kill other fish of similar size, including other arowanas. A single arowana in its own tank is the safest and most natural setup. Some keepers attempt to house them with very large, fast-moving fish like large plecos or large catfish, but even these combinations often fail when the arowana matures and becomes more aggressive.

Smaller fish—anything that fits in the arowana's mouth—are seen as food, not tankmates. Do not house them with tetras, danios, small cichlids, or any fish under 4 inches. The arowana's predatory instinct is not something training or habituation can override; it is hardwired behaviour.

If you want to keep multiple arowanas, they must be raised together from a young age in a very large tank (300+ gallons), and even then aggression often develops as they mature. Most experienced keepers recommend one fish per tank to avoid injury, stress, and death.

Common Health Problems and Prevention

Australian arowanas are hardy fish when water conditions are stable, but they are prone to a few specific issues. Eye problems—cloudiness, swelling, or one-sided blindness—often result from poor water quality, unbalanced lighting, or feeding from only one side of the tank. Prevent this by maintaining nitrate below 40 ppm, varying feeding positions, and providing moderate, even lighting.

Fin rot and bacterial infections appear as frayed fins or sores on the body and usually follow stress or poor water quality. A 25 percent water change and a review of tank conditions often resolve mild cases. Severe infections may require treatment with antibiotics prescribed by a veterinarian familiar with fish.

Parasites like gill flukes or intestinal worms can be introduced through live food or new fish. Quarantine any new additions for two to four weeks in a separate tank before introducing them to the main system. If parasites appear, a veterinarian can recommend appropriate medication.

Jumping is not a disease, but it is a leading cause of death in captive arowanas. These fish leap at insects and prey near the surface, and they will jump out of an open tank. A tight-fitting lid with small gaps for filter intake and heater is essential.

Lifespan and Long-Term Commitment

A well-cared-for Australian arowana lives 15 to 20 years in captivity, with some individuals reaching their mid-20s. This is a long-term commitment. Before purchasing one, confirm that you can maintain a large, heated tank for two decades, afford the equipment and food, and find a veterinarian who treats fish if problems arise.

As the fish ages, it may become less active and eat less frequently. This is normal. Older arowanas sometimes develop cataracts or slight cloudiness in the eye, but this does not always affect their quality of life. Monitor water quality closely in older fish, as they are more sensitive to poor conditions.

Legal Status and Where to Source One

Australian arowanas are legal to own in most countries, including the United States, Canada, and Europe, without special permits. This is one reason they are more accessible than Asian arowanas, which are protected and heavily regulated. Always check your local regulations before purchasing, as some regions or municipalities may have restrictions.

Source Australian arowanas from reputable breeders or established aquarium shops. Captive-bred fish are healthier and more adapted to aquarium life than wild-caught specimens. A healthy juvenile costs between $50 and $150, depending on size and source. Avoid extremely cheap fish, as they are often stressed, diseased, or poorly bred.

Frequently Asked Questions

Can I keep an Australian arowana with other fish?

Not reliably. Arowanas are predatory and territorial. Small fish are eaten; similarly sized fish are attacked. Some keepers house them with very large, fast-moving species like large plecos, but aggression often develops as the arowana matures. A single fish in its own tank is the safest approach.

How often should I feed my Australian arowana?

Juveniles eat once or twice daily. Adults do well on once-daily feeding or every other day. Feed only what the fish will eat in a few minutes. Arowanas are enthusiastic eaters and will beg, but overfeeding causes obesity and poor water quality.

What is the minimum tank size?

A single Australian arowana needs at least 150 gallons, though 180 to 250 gallons is more realistic for long-term health. The tank should be longer than it is tall, because arowanas are horizontal swimmers that need room to patrol and accelerate.

Do Australian arowanas need special lighting?

No special lighting is required, but moderate, even lighting is important. Twelve hours on and 12 hours off is standard. Excessive light or unbalanced lighting can contribute to eye problems, especially if the fish is fed from only one side of the tank.

How long do Australian arowanas live?

A well-cared-for Australian arowana lives 15 to 20 years, with some reaching their mid-20s. This is a long-term commitment that requires stable water conditions, consistent feeding, and access to fish veterinary care if problems arise.