Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Arapaima gigas


Arapaima gigas
Photos by Andy Rapson


Arapaima: From tupí-guaraní, arapaima.

General Notes:

Often said to be the worlds largest fresh water fish (it isn't) they are reported to reach 4.5 metres, (14.8 feet) but most specimens reach only half of this. Arapaima gigas are slow moving fish which ambush their prey. Their bodies are quite rigid and they need a lot of space even to turn around. Young fish are occasionally offered for sale in the aquarium trade but due to their size they make poor subjects for the aquarium. Arapaima gigas can live in areas where the water has an oxygen level which is very low. They achieve this by breathing atmospheric oxygen, something that they have to do every few minutes because their gills cannot provide them with all the oxygen that they need.


Arapaima gigas is a piscivore which means that it's main diet is smaller fish although it probably takes small mammals and birds if the opportunity presents itself.


There are no visible differences between the sexes.


Male Arapaima gigas build a nest in the substrate where the eggs will be laid in April or May. The male alone protects the brood.

Wild status

Wild populations are declining due to over fishing. The fish is now threatened  in the wild. Local fishermen use this to find their prey by carefully listening for the 'gulp' sound that the fish make when coming up for oxygen. Despite their threatened status they are still actively hunted as a food item

Information at a glance

pH: 6 - 6.5
dGH: 5 - 10
Temperature: 22 - 28°C (72 - 82°F)
Diet: Carnivore
Size: 4.5m (14.8ft)
Min tank size: - litres
Difficulty level: Do not keep
Aquarium type: -
Swimming level: middle / surface

Distribution and habitat

distribution map for Arapaima gigas

Origin: South America: Amazon River basin

Habitat: Slow moving or still water with very heavy vegetation


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Osteoglossiformes
Family: Arapaimidae
Sub-family: Heterotidinae
Genus: Arapaima
Species: A. gigas, (Schinz, 1822)

Common name:

Synonyms: Arapaema gigas, Sudis gigas, Sudis pirarucu, Vastres agassizii, Vastres arapaima, Vastres cuvieri, Vastres mapae.