The Arapaima is considered by many to be the largest freshwater fish in the world!

The Arapaima Arapaima gigas are very beautiful, but they arealso a fish that can get very large. Generally in the wild they will reach up to about 6.6 feet (200 cm) long, with the largest specimen reported to have attained almost 15 feet in length. In the aquarium they will seldom reach over 23.62 inches (60 cm).

These monster fish are also known as Pirarucu and Paiche. They are fast growers and powerful swimmers. They are a predator that mainly eats other fish. They will also jump out of the water to snatch small birds from low hanging tree branches. Because of their large size and food requirements, they are not really a good choice as a home pet for most aquarists. They need to be housed in a very large aquarium or pond.

This is a fish that is best suited for public aquariums as they have the facilities to keep something this large. There they can be fed live fish and kept in a tank containing 10,000 gallons or more. These fish are also illegal in many parts of the world, in large part because of the dangers of their release as they out grow their home aquariums.

Finding full grown specimens in the wild is a challenge for biologists. The Arapaima has never been considered common in its natural habitat, so it is not known exactly just how vulnerable this species is. Much of the natural habitat of the Arapaima is swamp type waters, and low in oxygen content. This fish has a lung type lining in its throat that enables it to breathe air from the surface. They need to surface about every 20 minutes for air.

The Arapaima has long been used as a food fish. These fish were at one time plentiful and fed many indigenous tribes of the Amazon. However its population has been decimated by fishing throughout its range. As the Arapaima must occasionally come to the surface and gulp air, that makes it particularly vulnerable. This gulp can be heard by fisherman who will then track down the fish and spear it, or catch it in large nets. The flesh of the Arapaima gigas is reputed to be very delicious, so it is much sought after by many in South America. It has also recently been introduced in Eastern Asia for fishing.


Scientific Classification


Arapaima – Quick Aquarium Care

Aquarist Experience Level:Expert
Aquarium Hardiness:Moderately hardy
Minimum Tank Size:1,000 gal (3,785 L)
Size of fish – inches177.0 inches (449.58 cm)
Temperament:Large Aggressive – Predatory
Temperature:75.0 to 84.0° F (23.9 to 28.9&deg C)

Habitat: Distribution / Background

The Arapaima Arapaima gigas was described by Schinz in 1822. They are found throughout much of the Amazon River basin. The exact habitat of these fish is unknown. It has been reported to be in the Essequibo basins and fossils have been found in the Rio Magdelena basin inn Colombia. These fish have been most recently been introduced in Eastern Asia for fishing. They have also been introduced to other regionswhere they have been released by pet owners.

They are found throughout much of the Amazon River basin in South America, as well as in flood plains. Much of its habitat is oxygen deficient. The Arapaima’s preferred habitat varies depending upon the season. During the dry season these fish will migrate to lakes and rivers and during the wet season seem to enjoy the food-rich forests. These fish can live in oxygen deficient water as it will breath from the surface, normally surfacing every 20 minutes.

In nature the adult Arapaima will feed on mainly fish and birds. Juveniles of this species have a much more varied diet of insects, fish larvae, crustaceans, and other smaller food sources.

  • Scientific Name: Arapaima gigas
  • Social Grouping: Solitary
  • IUCN Red List: DD – Data Deficient – The Arapaima is listed as data deficient on the IUNC Red List of Endangered species, and is listed on CITES: Appendix II.


The Arapaima is large and elongated with two small pectoral fins on the sides of the body close to the front. The coloration is gray with iridescent golden greens frontally extending back into blue greens with orange specks along the rest of the body, the fins are sometimes edged in red, and the belly is white. A unique characteristic is its tongue, which is bony or toothed.

This fish is said to be the largest of the freshwater fish. In the aquarium they will seldom reach over 23.62 inches (60 cm), and they have a lifespan of about 20 years. The young fish stay with their parents for the first 3 months and reach sexual maturity at 5 years.

In the wild the Arapaima will generally reach up to about 6.6 feet (200 cm) in length. Although the largest specimen was reported to have attained 14.8 feet (450 cm) in length, this is from an unconfirmed report from the first half of the 19th century. The maximum documented weight is 440 pounds (200 kg). Because of over fishing and the population growths of their natural habitat, these large fish are rarely found at maximum length and weight.

  • Size of fish – inches: 177.0 inches (449.58 cm) – They will seldom reach over 23.62 inches (60 cm) in captivity. Most reach about 6.6 feet (200 cm) in the wild.
  • Lifespan: 20 years – These fish will generally have a lifespan of 15 to 20 years in captivity.

Fish Keeping Difficulty

Due to the size and aggression of this fish, it is not recommended to even some of the most advanced fish keepers. Although the Arapaima are very adaptable to many different environments, they need for a huge tank, 1000 gallons or more, and powerful filters are a must. In captivity they will need live food, and larger live food as they grow. If you can meet their size and food needs they can me easily raised.

This is a fish that is best suited for public aquariums, they have the facilities to keep something this large. There it can be fed live fish and kept in a tank containing 10,000 gallons or more

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Expert – They require a very dedicated keeper to provide for their needs of an extremely large aquarium or pond and an ongoing diet of live foods.

Foods and Feeding

The Arapaima are carnivores, a predator that mainly eats other fish. They will also eat animals or birds if they are near by.They areknown to jump out of the water to snatch a small bird off of low-hanging tree branches. In captivity they can be fed smaller fish, chopped up meaty foods, crustaceans, pellets, and prepared foods such as krill and plankton.

  • Diet Type: Carnivore
  • Flake Food: No
  • Tablet / Pellet: Occasionally
  • Live foods (fishes, shrimps, worms): All of Diet
  • Meaty Food: All of Diet – Birds, fish, really anything in the water that they can get their mouth around. Be cautious, as reports of attacks on humans have been reported.
  • Feeding Frequency: Weekly

Aquarium Care

An Arapaima doesn’t place special demands on the water conditions, but the aquarium will need a very large filtration systems capable of handling the heavy bio-load this large of a fish can produce. They are quite adept at jumping so a vented canopy type top that tight fitting is suggested. A weekly water change of 15-20% is the standard recommendation.

  • Water Changes: Weekly – Water change should be 15-20% weekly.

Aquarium Setup

An Arapaima quickly gets extremely big so needs a very large home. If you plan on keeping one as a pet, be prepared to invest in a tank of 1,000 gallons or more, with 2500 gallons being best. As they are air gulpers, they need plenty of space at the surface and must have adequate oxygen available. So a wider aquarium is best with a square tank being ideal, and a vented canopy type top is suggested. They are quite adept at jumping so the canopy needs to be tight fitting.

They need a fine gravel substrate and a lot of swimming room. The Arapaima will spend most of its time in the middle or near the top of the water column. Because of the vast differences in the area that this fish lives the decor of the tanks can vary greatly. In general the aquarium needs to have a large surface area. They will appreciate dense vegetation on the sides and back, and some of the surface covered with floating plants, but also insure that there is plenty of open space at the surface.

  • Minimum Tank Size: 1,000 gal (3,785 L) – Provide an aquarium or pond the size of at least 1,000 gallons, with 2500 gallons being best.
  • Suitable for Nano Tank: No
  • Substrate Type: Small Gravel
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 75.0 to 84.0° F (23.9 to 28.9&deg C)
  • Range ph: 6.0-6.5
  • Hardness Range: 5 – 12 dGH
  • Brackish: No
  • Water Movement: Any
  • Water Region: All – Breathes from surface every 20 minutes.

Social Behaviors

The Arapaima is a predatory species. They have a large mouth and a large appetite so smaller fish will quickly become a meal. These fish are generally loners, and will be aggressive with others of their same species. These fish are best kept singly.

  • Temperament: Large Aggressive – Predatory
  • Compatible with:
    • Same species – conspecifics: No
    • Peaceful fish (): Threat – The Arapaima is a predatory species that eats fish.
    • Semi-Aggressive (): Threat
    • Aggressive (): Monitor – They will be aggressive unless the environment is very large with each species having its own territory. Difficult to achieve in the home aquarium.
    • Threat
    • Shrimps, Crabs, Snails: Threat – is aggressive
    • Plants: Safe

Sexual differences

Sexual differences are difficult to determine. During the breeding season, males are more colorful than the females, and have an exceptionally dark head.

Breeding / Reproduction

The Arapaima has been bred in captivity, The female becomes sexually mature at five years of age and about five and a half feet in length (168 cm). In the wild they are subject to the flood seasons, so will build their nest during the low water period from February through April. Then when the waters start to rise, the eggs hatch and there is abundant food for the young. They build a nest in a sandy area that’s about 20 inches wide and 6 inches deep. The female lays her eggs in the nest where they will be fertilized by the male. Both parents will guard the eggs and the fry. The young will then stay with their parents until about 3 months of age.

  • Ease of Breeding: Difficult

Fish Diseases

As with most fish the Arapaima are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. Remember anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance

These fish are hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won’t have to deal with health problems or disease. Because these fish eat live food, disease can be passed to them from their foods. Make sure to quarantine live food before feeding.

A good thing about Arapaima is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your fish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish is more likely to acquire disease.

Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Arapaima are not commonly available but when they are available they are quite pricey. Before you purchase this species, be sure to check with the Fish and Game Department or other environmental authorities in your area to be certain that you can keep one of these fish. In certain states they are banned from public and /or private possession, Texas being one. Most likely this is due to concerns that people may unwittingly release them into native waters.



 Arapaima gigas at National Zoo (Image Credit: Jeff Kubina, Wikimedia Commons CC BY-SA 2.0 Generic)