Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Heterotis niloticus

African bonytongue

African bonytongue, Heterotis niloticusAfrican bonytongue, Heterotis niloticus
Photos by Michelle Stuart


Heterotis: Greek, heteros = other + Greek, ous, otis = ear

General Notes:

The African bonytongue isn't really a species for the average fish tank, it is a very big heavily built fish which would need a large indoor pond if it was to thrive. Heterotis niloticus in deoxygenated waters; the hardiness of this fish, together with its great growth rate make it a candidate for aquaculture in Africa and it has been transported to a number of countries for this purpose.

 This fish is rarely offered for sale. These fish react aggressively to their own kind but will live peacefully with most other fish of a suitable size. African Bonytongues are nervous fish and are easily startled, in captivity this could lead to them damaging themselves by bumping in to tank/pond walls ect.

The fish is able to breathe atmospheric oxygen through its auxiliary branchial air breathing organs and so it is able to live in swamps where the water is very low in free oxygen.


The African bonytongue is a filter feeder which preys on small inverts. Smaller specimens will take insects, copepods, worms, crustaceans, bivalves as well as scavenge carcasses. It has a suprabranchial organ which has a sensory function, but also a mechanical function in concentrating the little food particles. The African Bonytongue is the only member of the order which is a filter feeder.


Unknown, there are no external differences between the sexes.


Heterotis niloticus breed in swampy regions during the wet season in to a prepared nest. The nest is built from vegetation and is normally about one metre in diameter and 20 to 60 cms deep and may rise above the waters surface. The fry remain in the nest for just a few days where they are guarded by the male alone. Captive breeding in the home aquaria is unknown due mainly to the size of the tank which would be required. The fry are born with external gills which are slowly covered as the fish matures.

Wild status

Very common across its range, due to its hardiness, growth rate and ultimate size it is an ideal candidate for aquaculture, so the fish has been extensively introduced beyond its natural range where it has had an adverse effect and become a pest.

Information at a glance

pH: 6 - 8
dGH: 5 - 19
Temperature: 25 - 30°C (78 - 86°F)
Diet: Micro predator
Size: 100cm (40in)
Min tank size: N/A litres
Difficulty level: Do not keep
Aquarium type: N/A
Swimming level: All levels

Distribution and habitat

distribution map for African bonytongue, Heterotis niloticus

Origin: Africa: Native in all the basins of the Sahelo-Sudanese region, the Senegal, Gambia, Corubal, Volta, Ouémé, Niger, Bénoue, Chad and Nile basins and Lake Turkana. Widely introduced beyond this range

Habitat: Open water of rivers and lakes, where they can be found in the pelagic zone as well as the littoral zone


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Osteoglossiformes
Family: Arapaimidae
Genus: Heterotis
Species: H. niloticus (Cuvier, 1829)

Common name:
African bonytongue, African arowana

Clupisudis niloticus,
Sudis nilotica,
Sudis adansonii,
Heterotis adansonii,
Sudis niloticus,
Heterotis adansoni,
Heterotis ehrenbergii