About Arapaima

Arapaima gigas, also known as pirarucu is a species of arapaima native into the basin of the Amazon River. Once thought to be the sole species in the genus, it is one of the largest freshwater fish. The species is an obligate air-breather and has to come to the surface regularly to gulp air.

Arapaima is the biggest freshwater fish in South America and one of largest freshwater fish in the world. Arapaima will grow to more than 2 meters (6.6 ft) long and weigh over 400 lbs OR 200 kilograms. It feeds on other fish species and at times it may even jump from the water to catch a snack such as a bird or little land mammal. Additionally, this fish can breathe air and remain underwater for 15-20 minutes at a time and can also survive up to 24 hours out the water.

Arapaima is the biggest freshwater fish
IGFA world record for the fish of 339 pounds (154 kg)

A. gigas has a streamlined body with dorsal and anal fins set well back towards the tail. Though the body is mainly gray to gray-green, its Brazilian neighborhood name”pirarucu” derives from the indigenous word for”red fish”, thought to refer to the red flecks on the scales towards the tail or the reddish-orange colour of its meat.

Notable for their bony tongues, Arapaima breathe air and can survive in oxygen poor water – a trait that allows them to live in stagnant and otherwise inhospitable conditions. They are also known to leap out of the water to catch birds and small mammals on overhanging branches.


Arapaima in Aquarium

Arapaimas can grow over 2 meters (6.6 feet) in length and weigh up to 200 kilograms (440 lbs). Their unique physiology includes a labyrinth organ, which allows them to breathe air, and enables them to survive in oxygen-depleted waters. This characteristic necessitates access to the water surface in an aquarium for air gulping. Despite their size, Arapaimas are not usually aggressive towards other fish but can exhibit predatory behavior towards much smaller species.

Housing Requirements

Due to their massive size, the tank housing an Arapaima must be extraordinarily large, wide, and long enough for them to move and turn comfortably. The tank design also needs to account for these fish’s behavior of leaping out of the water, a natural hunting trait. Adequate cover and a secure top are crucial to prevent accidental escape or injury. A minimum of 1,000 gallons is recommended, but 2,500 gallons is ideal.

The aquarium should be decorated with large rocks and plants to provide hiding places for the fish. Arapaimas are not aggressive fish, but they can be territorial, so it is important to give them plenty of space.

Water Quality

Arapaimas thrive best in warm, soft, slightly acidic water, similar to their Amazonian habitat. Constant monitoring and maintenance of the tank water, including parameters like temperature, pH, and nitrate levels, are vital to their health. Though resilient, maintaining optimal conditions can prevent stress and potential health issues. The water should be changed 15-20% every week.


In their natural habitats, Arapaimas are apex predators, feasting on fish, crustaceans, and even small land animals. An aquarium diet must, therefore, include high-protein options like chunks of fish, shrimp, and specially formulated carnivorous fish pellets. Careful portion control is necessary to ensure health without overfeeding. They should be fed twice a day, and their diet should be supplemented with vitamin and mineral supplements.

Tank Mates

Selecting tank mates for Arapaimas is a process that requires careful thought. They generally do well with other large, non-aggressive species. Smaller fish might trigger their predatory instincts and should be avoided.

Care Level: Expert

Temperament: Snot aggressive

Maximum Size: 104″

Minimum Tank Size: 2500 gallons

Water Conditions: 75-86° F, KH 8-12, pH 6.0-7.5

Diet: Carnivore

Origin: Amazon, Orinoco River Basin

Family: Osteoglossidae

Species: Arapaima

With proper care, Arapaimas can live for up to 20 years in captivity. They are a fascinating and rewarding fish to keep, but they are not for the faint of heart. Arapaimas can make a beautiful and interesting addition to any aquarium.

Arapaima Farming
Arapaima Farming

Super Red Arapaima Gigas // Siriwan farm

By fishexp