The Arowana in the Aquarium Hobby: Beauty, Challenge and Responsibility

Few freshwater fish command attention quite like the arowana. With its long, streamlined body, metallic scales, powerful upward-facing mouth and two distinctive barbels, an arowana looks less like an ordinary aquarium fish and more like a creature from an ancient legend.

Often called the dragon fish, the arowana has become a symbol of prestige within the aquarium hobby. Its slow, graceful movement gives it an almost regal appearance, while its alert personality makes it feel more like a true aquatic pet than a decorative display animal. However, behind that beauty is a demanding predator that requires considerable space, specialised equipment and a long-term commitment.

What Is an Arowana?

Arowanas belong to the bonytongue group of freshwater fishes. Their name refers to a hard, tooth-bearing structure on the floor of the mouth. Most species have an elongated body, very large scales and a mouth positioned to capture food from the water’s surface.

The silver arowana, one of the most familiar species in the hobby, is native to South America. It can reach approximately 90 centimetres in recorded total length, while some sources report even larger specimens. Its upward-facing mouth allows it to attack prey from below, and wild fish are capable of jumping out of the water to capture insects. (FishBase)

Arowanas are therefore not simply large community fish. They are surface-dwelling predators built to patrol open water, detect movement above them and strike with remarkable speed.

Popular Arowanas in the Hobby

Several species appear in the aquarium trade, although their availability, price and legal status differ considerably.

Silver Arowana

The silver arowana, Osteoglossum bicirrhosum, is usually the most widely available and affordable option. It has a bright silver body, long fins and a particularly graceful swimming style. Juveniles are often sold at manageable sizes, but adults can approach 90 centimetres and require an exceptionally large aquarium. (FishBase)

Its relatively low purchase price can be misleading. The fish may be affordable, but the adult aquarium, filtration, food and electricity certainly are not.

Black Arowana

The black arowana, Osteoglossum ferreirai, originates from the Rio Negro basin in South America. Young black arowanas have attractive dark markings and contrasting colour, although their appearance becomes more similar to the silver arowana as they mature. The species can also reach about 90 centimetres. (FishBase)

Asian Arowana

The Asian arowana, Scleropages formosus, includes highly prized green, gold and red colour varieties. These fish are especially important in parts of Asian aquarium culture, where they are associated with prosperity, status and good fortune.

This species is listed as Endangered and appears in CITES Appendix I. Its international trade is therefore tightly controlled. Legal captive-breeding operations exist, and fish produced by registered facilities may be individually marked and accompanied by documentation, but ownership and import rules still vary between countries. (FishBase)

An Asian arowana should never be purchased without verifying its legal origin, identification and paperwork.

Australian Arowanas

The jardini or Australian bonytongue, Scleropages jardinii, is another impressive species. It occurs naturally in northern Australia and parts of New Guinea and may reach around one metre in length. It is a territorial surface feeder that consumes insects, fish, frogs and crustaceans. (FishBase)

Australian species are often robust, but they can be challenging to combine with other large fish because of their territorial nature.

Why Hobbyists Are Drawn to Arowanas

The appeal of an arowana is difficult to explain until one is seen moving through a properly designed aquarium. It rarely swims frantically. Instead, it patrols the upper level of the tank with slow, deliberate movements.

Many specimens also become highly aware of activity outside the aquarium. They may recognise feeding routines, follow their keeper along the glass and respond when someone enters the room. This combination of size, intelligence-like behaviour and visual presence gives the arowana a personality that few freshwater fish can match.

There is also the excitement of keeping a specialised predator. Watching an arowana accurately take floating food from the surface can be spectacular. Yet this feeding response is also a reminder that the fish is a powerful jumper and must be housed accordingly.

The Real Challenge: Aquarium Size

Space is the most important consideration when keeping an arowana. A juvenile may appear comfortable in an ordinary aquarium, but that situation is temporary. Arowanas grow into long, active fish that need enough room to swim naturally and turn without rubbing their bodies or damaging their barbels.

Length and width are more important than height. Although some general care guides describe 150 gallons as a starting point, veterinary guidance notes that adult arowanas require at least 250 gallons. Specialist long-term recommendations can be considerably larger; one experienced-fishkeeping source recommends a footprint of approximately three metres by one metre for an adult Asian arowana. (PetMD)

The exact requirement depends on the species and adult size, but the main lesson is simple: an adult arowana aquarium should be planned in metres, not merely in litres.

Purchasing a juvenile with the intention of finding a bigger tank later is risky. Large aquariums are expensive, heavy and difficult to install. They may require reinforced flooring, custom stands, specialised filtration and professional construction. The responsible approach is to organise the adult enclosure before purchasing the fish.

Creating a Suitable Environment

An arowana aquarium should provide a long, open swimming route near the surface. Decorations must not overcrowd the tank, and sharp rocks or branches should be avoided because a startled fish can collide with them.

A strong, rigid lid is essential. Every opening around pipes, cables and filters should be secured. Arowanas are powerful jumpers, particularly when frightened by sudden movement, loud noises or abrupt changes in lighting. Gradually illuminating the room before switching on bright aquarium lights may help reduce startling. (PetMD)

The aquarium should also be positioned in a relatively calm area. Constant foot traffic, banging doors and reflections can make some individuals nervous.

Filtration and Water Quality

A large predator eating protein-rich food produces a substantial amount of waste. Oversized mechanical and biological filtration is therefore essential. Large canister filters may work for younger fish, while adult systems often benefit from a properly designed sump or another custom filtration arrangement. Redundant filtration is valuable because the failure of a single pump or filter can quickly become dangerous in a heavily stocked system. (Practical Fishkeeping)

Ammonia and nitrite should remain at zero, while nitrate must be controlled through appropriate feeding, filtration and regular water changes. Temperature, pH and other parameters should remain stable rather than swinging between extremes.

Silver and black arowanas are tropical fish associated with temperatures around 24–30°C. General captive-care guidance commonly recommends warm, mildly acidic water, although the precise target should be adjusted for the species, source water and conditions in which the individual fish was raised. (FishBase)

Consistency is more valuable than repeatedly adding chemicals to chase a supposedly perfect number.

Feeding an Arowana

Arowanas feed primarily near the surface. Their body shape and upward-facing mouth are designed for attacking fish, insects and other animals from below. In the wild, silver arowanas may even leap from the water to catch large insects. (FishBase)

In captivity, a high-quality floating pellet or stick made for large carnivorous fish can form the foundation of the diet. This may be supplemented with suitable foods such as shrimp, fish, insects and worms. Variety helps provide more balanced nutrition than relying on a single food. (PetMD)

Overfeeding should be avoided. Large portions increase waste and can quickly damage water quality. Uneaten food should be removed, and frozen foods should be fully thawed before feeding.

An arowana that accepts prepared pellets is usually easier and safer to maintain than one conditioned to demand live prey. Routine use of feeder fish can introduce parasites or disease and may encourage the arowana to refuse more balanced prepared foods.

Behaviour and Tank Mates

Arowanas are often kept alone. Their size, predatory instincts and territorial behaviour make community planning difficult. Small fish will eventually be treated as food, while aggressive or fin-nipping tank mates can injure the arowana’s fins, scales and sensitive barbels.

Where tank mates are attempted, they must be too large to swallow and should generally occupy a different level of the aquarium. Large bottom-dwelling fish are sometimes selected, but success is never guaranteed. Individual temperament, aquarium dimensions and competition at feeding time all influence the outcome. (PetMD)

Adding more fish also increases the biological load, meaning an already large aquarium may need to become even larger.

Interestingly, arowanas show sophisticated parental care. Male silver arowanas carry the eggs, larvae and early juveniles in their mouths for nearly six weeks. This mouthbrooding behaviour helps protect the young during their vulnerable early development. (FishBase)

Health and Long-Term Care

Healthy arowanas normally have clear eyes, intact fins, a strong appetite and an active swimming pattern near the surface. Warning signs include rapid breathing, loss of appetite, cloudy eyes, abnormal swimming, damaged fins, raised scales or prolonged resting near the bottom. (PetMD)

Jumping injuries and collisions are particularly serious risks. An arowana may damage its jaw, lose scales or suffer internal injuries after striking the lid or aquarium walls. Poor water quality can contribute to fin damage, infections and other chronic health problems.

“Drop-eye,” where one or both eyes point downward, is also seen in captive arowanas. Its causes are debated, and prevention is not always straightforward. Spacious housing, appropriate surface feeding, safe surroundings and good general husbandry remain the sensible priorities.

With proper care, arowanas commonly represent a commitment of 10 to 20 years or longer. (PetMD)

Legal and Ethical Responsibility

Before buying any arowana, the keeper must research local wildlife, import and invasive-species regulations. Rules can apply not only to Asian arowanas but also to other species in particular countries, provinces or states.

For regulated fish, documentation should be checked before money changes hands. Suspiciously cheap, undocumented or incorrectly identified specimens should be avoided. Supporting legal captive breeding helps reduce pressure on wild populations and protects the keeper from serious legal problems.

An unwanted arowana must never be released into a river, dam or local waterway. Rehoming a metre-long predator can be extremely difficult, which is another reason the decision to keep one must be made with its full adult size in mind.

Is an Arowana Right for You?

An arowana may be suitable when the keeper has:

• Space for a genuinely adult-sized aquarium

• Strong, reliable filtration and backup equipment

• A secure lid and safe swimming environment

• Experience maintaining stable water quality

• A realistic long-term food and electricity budget

• Access to legally sourced fish and any required documentation

• A plan for emergencies, power failures and veterinary care

For beginners, there are many smaller surface-dwelling fish that offer interesting behaviour without requiring a room-sized aquarium. Admiring an arowana does not automatically mean owning one is the right decision.

Final Thoughts

The arowana deserves its legendary status in the aquarium hobby. It is beautiful, powerful and endlessly fascinating to observe. In the correct environment, a healthy adult gliding through open water can become the centrepiece of an extraordinary freshwater display.

However, the true measure of a successful arowana keeper is not the price or colour of the fish. It is the ability to provide enough space, excellent water quality, appropriate nutrition and responsible care throughout the animal’s life.

An arowana is not simply another aquarium purchase. It is a major commitment - and when that commitment is respected, keeping one can be among the most rewarding experiences in the freshwater fishkeeping hobby.