What a Black Arowana Is and Where It Comes From

The black arowana is a large, sleek freshwater fish native to South America, primarily the Amazon River basin and other river systems in Brazil, Peru, and Colombia. It is one of several arowana species kept in home aquariums, distinguished by its dark coloring, elongated body, and the way it hunts—striking upward at the water's surface to catch prey. Black arowanas are predatory fish that can grow to 3 to 4 feet in length, though some individuals reach larger sizes in the wild.

In the aquarium hobby, black arowanas are prized for their appearance and behavior, but they demand specific conditions and a long-term commitment. They are not beginner fish. A black arowana can live 15 to 20 years in captivity with proper care, and some live longer. Before acquiring one, you need to understand the tank size required, feeding costs, and the legal restrictions that apply in many regions.

Key Takeaways

  • Black arowanas require a minimum tank of 120 gallons for a single fish, though 150 gallons or larger is better, because they are active swimmers that need horizontal space.
  • These fish are carnivorous and will eat smaller fish, so tank mates must be large enough not to fit in their mouth, and even then compatibility is limited.
  • Water temperature must stay between 72 and 82 degrees Fahrenheit, and the tank needs strong filtration because arowanas produce significant waste.
  • Many regions restrict or ban the import and ownership of black arowanas due to conservation concerns, so check your local and state regulations before purchasing.
  • Black arowanas are expensive fish, often costing $100 to $300 or more depending on size and coloration, and the tank setup and ongoing care add substantial cost.

Tank Size and Water Conditions

A black arowana needs a minimum tank volume of 120 gallons, but 150 gallons or larger is more realistic for long-term health. These fish are active swimmers that patrol the water column and need horizontal length more than height. A 48-inch-long tank is a practical baseline; a 60-inch tank is better. The fish will become stressed and aggressive in cramped quarters, and stress shortens lifespan and increases disease risk.

Water temperature should remain between 72 and 82 degrees Fahrenheit. Most keepers maintain the tank around 76 to 78 degrees. Black arowanas come from warm tropical rivers, so a reliable aquarium heater is essential. The water should be slightly acidic to neutral—a pH between 6.0 and 7.0 is ideal. Hardness is less critical, but soft to moderately hard water (4 to 8 dGH) mimics their natural habitat.

Filtration must be robust. Black arowanas are heavy feeders and produce substantial bioload. A canister filter rated for 200 to 300 gallons per hour is a reasonable starting point for a 120-gallon tank, though many keepers use two filters or oversized single units. Weekly water changes of 25 to 30 percent are standard practice. Test ammonia, nitrite, and nitrate regularly; ammonia and nitrite should always read zero, and nitrate should stay below 40 ppm.

Feeding and Diet

Black arowanas are obligate carnivores. In the wild, they eat fish, insects, crustaceans, and small vertebrates. In captivity, they will consume live or frozen fish, large insects, and specialized carnivore pellets. Many keepers feed a combination: frozen silversides or smelt two to three times per week, supplemented with live feeder fish occasionally, and high-quality pellets on other days.

Feeding frequency depends on the fish's age and size. Juveniles eat more often—once or twice daily—while adults do well on feeding every other day or five times per week. Overfeeding leads to obesity, poor water quality, and shortened lifespan. A good rule is to offer an amount the fish can consume in a few minutes, then remove uneaten food.

Live feeder fish carry disease risk, so frozen options are safer. If you use live feeders, quarantine them first and source them from reputable suppliers. Some keepers avoid live feeders entirely and condition their arowanas to accept frozen or pellet food, which is more economical and reduces disease exposure.

Tank Mates and Behavior

Black arowanas are aggressive predators and have limited compatibility with other fish. They will eat anything small enough to fit in their mouth, including small tetras, guppies, and even young cichlids. Tank mates must be large, robust fish that cannot be swallowed and that will not nip at the arowana's fins or scales.

Suitable companions include large plecos, large catfish species, adult oscars, and large cichlids such as Jaguars or Vieja species. Even with compatible tank mates, aggression can develop as the arowana grows. Some keepers keep black arowanas alone to avoid conflict and stress. If you choose tank mates, observe behavior closely and be prepared to separate fish if fighting occurs.

Black arowanas are intelligent and will recognize their keeper. They often surface to feed and can be trained to eat from the hand. However, they are not social in the way that schooling fish are. They do not need companionship, and solitary housing is often the safest option.

Legal Restrictions and Availability

Before purchasing a black arowana, research the regulations in your state, province, or country. Many regions restrict or prohibit the import and ownership of black arowanas because they are listed as endangered or threatened in their native range. The Convention on International Trade in Endangered Species (CITES) regulates the trade in arowanas, and some species are protected under national laws.

In the United States, regulations vary by state. Some states allow black arowanas with a permit; others ban them outright. California, for example, prohibits the import of many arowana species. Canada has similar restrictions. In Europe, regulations differ by country. Before you buy, contact your state's fish and wildlife agency or your country's environmental ministry to confirm what is legal in your area.

Reputable dealers will ask for proof of legal residency and may require documentation before selling. If a seller does not ask questions about your location, that is a red flag. Purchasing an illegally imported fish supports the black market and harms wild populations.

Common Health Issues and Lifespan

Black arowanas are generally hardy when kept in proper conditions, but several health problems can arise. Fin rot and scale damage often result from poor water quality or aggressive tank mates. Swim bladder disease can occur if the fish is overfed or if water temperature fluctuates. Parasitic infections are possible, especially if live feeders are introduced without quarantine.

Prevention is the best approach: maintain stable water conditions, perform regular water changes, feed appropriately, and quarantine any new fish or feeders before introducing them to the main tank. If illness appears, isolate the fish in a hospital tank and treat according to the specific diagnosis. Many arowana keepers consult experienced aquarists or veterinarians familiar with exotic fish.

With proper care, a black arowana typically lives 15 to 20 years, and some individuals have been documented living longer. This is a long-term commitment. Before acquiring one, consider whether you can maintain the tank, manage the cost, and provide appropriate care for two decades or more.

Cost and Long-Term Commitment

The initial investment for a black arowana setup is substantial. The fish itself costs $100 to $300 or more, depending on size, coloration, and source. A suitable 120-gallon tank, stand, canister filter, heater, lighting, and substrate will run $800 to $1,500 or more. Décor, plants, and additional equipment add further cost.

Ongoing expenses include electricity for heating and filtration, food (which is not cheap for a large carnivore), water testing supplies, and occasional equipment replacement. Annual costs for a single black arowana typically range from $300 to $600, though this varies with local electricity rates and feeding choices.

This is not an impulse purchase. Black arowanas are for keepers who have researched the species, confirmed legal status in their area, and committed to the long-term care and expense. They reward that commitment with striking appearance and interesting behavior, but only if their needs are met consistently.

Frequently Asked Questions

Can I keep a black arowana in a 75-gallon tank?

No. A 75-gallon tank is too small for an adult black arowana. These fish grow to 3 to 4 feet and need horizontal swimming space. A 120-gallon minimum is the standard recommendation, and larger is better. Undersized tanks cause stress, aggression, and shortened lifespan.

Will a black arowana jump out of the tank?

Yes, they can and do. Black arowanas are surface feeders that strike upward at prey, and they may leap out of the water if startled or pursuing food. A secure, fitted lid or hood is essential. Leave no gaps where the fish could escape.

How often should I feed a black arowana?

Adults typically eat every other day or five times per week. Juveniles eat more frequently—once or twice daily. Adjust based on the fish's size and appetite. Overfeeding causes obesity and poor water quality, so offer only what the fish will consume in a few minutes.

Are black arowanas illegal to own?

It depends on where you live. Many states and countries restrict or ban black arowanas due to conservation concerns. Check with your state fish and wildlife agency or environmental ministry before purchasing. Some regions allow ownership with a permit; others prohibit it entirely.

What is the difference between a black arowana and other arowana species?

Black arowanas are dark-colored and native to South America. Other species include the silver arowana (also South American, lighter in color), the Asian arowana (from Southeast Asia, highly regulated), and the African arowana (from West Africa). Care requirements are similar, but legal status and availability differ significantly by species and region.