African arowana

Heterotis niloticus

Also known as Heterotis

FreshwaterFish

African arowana (Heterotis niloticus) — (c) Brent Tibbatts, some rights reserved (CC BY) · cc-by

Care at a glance

Temperature: 75–82°F (24–28°C)
pH: 6.2–7.8
Adult size: 39.4 in (100 cm)
Minimum tank: 528 gal (2,000 L)
Temperament: Mostly peaceful
Social behavior: Solitary
Tankmates: Tankmates with caution
Swim level: Middle
Difficulty: Difficult
Breeding: No record
Rarity: Rare
Origin: Nile and West African basins
Family: Arapaimidae

Overview

This is a giant, mostly peaceful bonytongue that grows to about a metre, so honest housing is pond scale rather than an ordinary aquarium. Despite its size it is not a hunter: it feeds by straining tiny food from the water, so it will not chew up tankmates the way a predator does, but its bulk and boisterous feeding mean any companions must be large and robust, and it is simplest kept alone. Choose tankmates with real caution if at all. Feed small foods and prepared items: fine pellets, plankton foods, and finely chopped meaty foods. Plan on at least 2000 litres and a very long-term commitment.

In the wild

It ranges across the Nile and the rivers and floodplains of much of West and central Africa, cruising large, warm, slow waters and seasonally flooded plains. Recreate the water rather than the scale: warm, 24 to 28 degrees Celsius, with a soft to neutral pH of 6.2 to 7.8 and gentle flow. Open swimming volume matters far more than decor, and only a very large system or pond comes close.

Good to know

It belongs to the family Arapaimidae and is the smaller African cousin of the giant arapaima, reaching about 100 cm. Alone among the bonytongues it is a filter feeder, straining plankton and fine particles from the water through a specialised coiled organ above its gills. It is not reliably bred in home aquaria, though it nests and is farmed for food in parts of Africa.

Did you know

It is an arowana relative that gave up hunting for filter feeding. A coiled organ above its gills gathers plankton and fine particles into a mass the fish can swallow, making it the only bonytongue to feed this way.