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Regions > African Rainforest > Aba aba

Aba aba

Location at the Zoo: African Rainforest



Region:

Africa

Class:

Osteichthyes

Order:

Osteoglossiformes

Family:

Gymnarchidae

Genus:

Gymnarchus

Scientific Name:

Gymnarchus niloticus

Description

: This fish has no pelvic, anal or caudal fins. The dorsal fin begins just behind the head and continues along the back resembling a ribbon like fringe. Aba abas have a compressed body which tapers to a finger like tail that extends beyond the end of the dorsal fin. The length can be up to 165 cm and the weight up 18.5 kg. The fish has eyes which are very much reduced in size with respect to the size of the body. Generally, they are grey-brown in colour.

Distribution

: Africa: occurring widely in the Nile, Niger, Volta, Chad, Senegal and Gambia basins, and Lake Rudolf.

Habitat

: Freshwater - Tropical: river and lakes with still, muddy water conditions.

Food

: They feed on crustaceans, insects and fish. Generally the young of the species feed on insects and other invertebrates.

Reproduction and Development

: A floating nest of grass and other plant fragments is constructed in which approximately 1000 amber coloured eggs 0.4 - 1.0 cm in diameter, are laid, fertilized and guarded. When the young hatch they have long gill filaments and a trailing yolk sac and have been seen regularly coming to the surface for air.

Adaptations

: The Aba aba possesses an electric organ that extends along almost the entire trunk to the tip of the tail. It is also equipped with ampullary receptors and two types of tuberous receptors for electroreception. The fish is very sensitive to disturbances in the electric field, which it produces around itself in pulses or shorter bursts, and in this way can detect prey, predators and its own species. In addition, the electric field is used for navigation. Because the Aba aba generally lives in muddy/turbid waters, their vision is severely limited and so they must rely on their electric field to "see" what is around them. Aba abas can move equally well forwards or backwards by reversible wave-like movements travelling along the dorsal fin while keeping the body rigid, but it prefers to remain still to reduce distortion of electrical field.

Threats to Survival

: The risk of overexploitation as a source of food.

Status

: IUCN: Least Concern; CITES: Not Listed

Zoo Diet

: Fish gelatine, beef heart gelatine, scallops, and shrimp.


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