What an Asian Arowana Is and Why They Matter

The Asian arowana is a large, predatory freshwater fish native to Southeast Asia—primarily Malaysia, Thailand, and Indonesia. It is one of the most expensive and sought-after aquarium fish in the world, with some specimens selling for thousands of dollars. The fish can reach 24 to 36 inches in length and live 20 to 30 years in captivity, making it a long-term commitment rather than a casual purchase.

Asian arowanas are prized for their metallic scales, which shift between silver, gold, red, and bronze depending on the individual and lighting. They are also highly intelligent, recognizing their owners and responding to feeding routines. However, they are not beginner fish. They require large tanks, specific water conditions, and careful feeding management to thrive.

In many countries, including the United States, Asian arowanas are protected under the Convention on International Trade in Endangered Species (CITES). This means they can only be legally owned if they were bred in captivity and come with proper documentation. Importing or selling wild-caught specimens is illegal.

Key Takeaways

  • Asian arowanas require a minimum tank size of 250 gallons and preferably 300+ gallons to accommodate their size and swimming behavior.
  • These fish are carnivorous and will eat smaller fish, shrimp, and invertebrates, so tank mates must be large enough not to be viewed as prey.
  • Water temperature should stay between 72 and 82°F, with neutral to slightly acidic pH and regular water changes to maintain quality.
  • Legal ownership in most countries requires CITES documentation proving the fish was captive-bred, not wild-caught.
  • The initial cost of the fish itself ranges widely, but quality specimens often exceed $500, and the tank setup and ongoing care add significant expense.

Tank Size and Physical Setup

An Asian arowana needs a minimum tank size of 250 gallons, though 300 gallons or larger is strongly recommended. The fish grows quickly and requires substantial horizontal swimming space. A 6-foot-long tank is the practical minimum; 8 feet is better. The tank should be at least 2 feet deep and 2 feet wide to allow the arowana to turn comfortably and exhibit natural behavior.

The tank must have a tight-fitting lid. Arowanas are powerful jumpers and will leap out of open tanks, especially when startled or during feeding. A mesh or acrylic cover prevents escape and injury. Avoid sharp decorations or tank edges that could damage the fish's delicate mouth or scales.

Substrate choice is flexible—sand or fine gravel works well. Many keepers use minimal substrate to simplify cleaning. Driftwood and large rocks can be added for visual interest, but the arowana needs open swimming space more than elaborate decoration. Live plants are optional and often unnecessary; the fish may uproot or damage them.

Water Conditions and Filtration

Asian arowanas thrive in warm, clean water. The ideal temperature range is 72 to 82°F, with 75 to 80°F being optimal. A reliable aquarium heater is essential, as temperature swings stress the fish and make it susceptible to disease. Use a thermometer to monitor daily.

pH should be neutral to slightly acidic, between 6.0 and 7.0. Water hardness (GH) should be soft to moderate, ideally 4 to 8 dGH. These parameters are less critical than temperature but should remain stable. Sudden shifts in pH or hardness can trigger stress and illness.

Filtration must be powerful and reliable. A canister filter rated for 300+ gallons per hour is standard for a 250-gallon tank. Many keepers use two filters for redundancy. The arowana produces significant waste, so strong mechanical and biological filtration is necessary. Perform 25 to 50 percent water changes every one to two weeks, depending on bioload and filter efficiency. Never let ammonia or nitrite rise above zero; nitrate should stay below 40 ppm.

Feeding and Diet

Asian arowanas are strict carnivores and will not eat plant matter or prepared flakes. They hunt live prey in the wild and prefer moving food in captivity. Suitable foods include live or frozen feeder fish (such as silversides, mullet, or mackerel), large shrimp, crayfish, and insects like crickets or grasshoppers.

Feed juveniles daily or every other day; adults can be fed every two to three days. Portion size should be roughly the size of the fish's eye—not the entire head, as overfeeding leads to bloating and poor water quality. Many keepers rotate food types to provide variety and balanced nutrition.

Live feeder fish carry disease risk and can injure the arowana if they are too large or aggressive. Frozen food is safer and more convenient. Thaw frozen items in tank water before feeding, or use a feeding ring to contain the food and prevent it from scattering and fouling the tank.

Tank Mates and Behavior

Asian arowanas are solitary, aggressive fish and should be kept alone in most cases. They will eat any fish small enough to fit in their mouth—including other arowanas. Even fish that seem too large may be attacked or harassed, especially as the arowana matures.

Some keepers have successfully housed arowanas with very large, aggressive fish such as large plecos, large catfish, or large cichlids, but this requires careful observation and a very large tank. The risk of injury or stress is always present. For most hobbyists, a single arowana in a dedicated tank is the safest and most practical approach.

Arowanas are intelligent and curious. They recognize their owners, respond to feeding routines, and may follow your hand along the glass. However, they are not social and do not benefit from the presence of other fish. Solitary housing is not cruel—it is what the species requires.

Health Issues and Common Problems

Healthy arowanas are hardy, but poor water conditions, stress, and improper diet cause illness. Swim bladder disorder is common in young fish and can result from rapid temperature changes, poor diet, or constipation. Affected fish may float at the surface or sink to the bottom. Treatment involves stable water conditions, varied diet, and sometimes fasting for a day or two.

Mouth rot and scale damage occur when the fish injures itself on tank edges or sharp objects. Prevention is the best approach: use smooth decorations, rounded tank edges, and a secure lid. If injury occurs, perform frequent water changes and watch for secondary bacterial infection.

Parasites and bacterial infections can develop in poor water conditions. Maintain consistent temperature, perform regular water changes, and feed a varied diet to keep the immune system strong. Quarantine any new fish before adding them to the tank, though this is moot if the arowana is housed alone.

Legal Ownership and Documentation

In the United States and most developed countries, Asian arowanas are protected under CITES Appendix I. This means they can only be legally owned if they were captive-bred and come with proper documentation—typically a CITES certificate or import permit. Purchasing an arowana without documentation, or buying a wild-caught specimen, is illegal and can result in fines or confiscation.

Reputable breeders and aquarium retailers provide documentation with every sale. If a seller cannot provide proof of captive breeding and legal import, do not purchase the fish. Some countries have additional restrictions; check your local and state regulations before buying.

If you already own an arowana without documentation, contact your local fish and wildlife agency for guidance. In some cases, you may be allowed to keep the fish but not sell or transfer it. Attempting to hide an illegally owned arowana can result in serious penalties.

Cost and Long-Term Commitment

The total cost of keeping an Asian arowana extends far beyond the purchase price. A quality specimen typically costs $500 to $2,000 or more, depending on size, coloration, and breeder reputation. The tank setup—including the aquarium, filtration, heater, lighting, and stand—can easily exceed $1,500 to $3,000. Ongoing costs include electricity, water, food, and maintenance supplies.

Over a 20 to 30-year lifespan, the total investment can reach $10,000 or more. This is not a casual hobby purchase. Prospective owners should be prepared for a decades-long commitment and the financial responsibility that comes with it. If circumstances change—moving, job loss, or loss of interest—rehoming an adult arowana can be difficult, as few aquariums are large enough to accommodate it.

Frequently Asked Questions

Can I keep two Asian arowanas together?

No. Adult arowanas are highly territorial and will fight to the death. Even juveniles raised together will eventually become aggressive as they mature. A single arowana per tank is the only safe option.

What is the difference between Asian and other arowana species?

Asian arowanas are the most expensive and sought-after species, prized for their metallic coloration and size. South American arowanas (silver and black species) are larger, less expensive, and more readily available. Australian arowanas are smaller and less common. All require large tanks and carnivorous diets, but Asian arowanas are the most demanding in terms of cost and legal restrictions.

Do Asian arowanas need a specific type of lighting?

No special lighting is required for the fish's health, but moderate lighting enhances the metallic sheen of the scales. Standard aquarium lighting is sufficient. Avoid very bright or constant lighting, as it can stress the fish. A 10 to 12-hour day-night cycle is natural and healthy.

How do I know if my arowana is healthy?

A healthy arowana is active, responsive to feeding, and has smooth scales with no visible damage. The eyes should be clear and bright. Gills should move steadily. Avoid fish that float, sink, or show lethargy, as these are signs of illness or poor conditions.

Can I transport an adult arowana to a new tank or home?

Yes, but it requires careful planning. Use a large, well-oxygenated transport container and keep the journey as short as possible. Minimize stress by keeping the fish in darkness during transport and avoiding sudden temperature changes. Acclimate the fish slowly to the new tank over 30 to 60 minutes using the drip method.