Gymnarchus niloticus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Osteoglossiformes Gymnarchidae

Scientific Name: Gymnarchus niloticus Cuvier, 1829
Regional Assessments:
Common Name(s):
English Aba, Aba aba, Frankfish, Freshwater Rat-tail
Gymnarchus electricus Sauvage, 1880

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: 2009-05-01
Assessor(s): Azeroual, A., Entsua-Mensah, M., Getahun, A., Lalèyè, P., Moelants, T. & Vreven, E.
Reviewer(s): Snoeks, J., Tweddle, D., Getahun, A., Lalèyè, P., Paugy, D., Zaiss, R., Fishar, M.R.A & Brooks, E.
This species has a wide distribution, with no known major widespread threats. It is therefore listed as Least Concern. It has also been assessed regionally as Least Concern for western Africa. In eastern Africa, it is categorized as Vulnerable. Due to a lack of information on the species distribution and threats in north and northeast Africa, it has been categorized as Data Deficient. It could even be Regionally Extinct within north Africa.

Geographic Range [top]

Range Description:Gymnarchus niloticus naturally occurs from Senegal to Ethiopia.

Central Africa: According to Thys van den Audenaerde (1966) the species has been introduced from Fort-Lamy, Chad to Yaoundé, Cameroon. Its presence is not confirmed by museum records. It is unknown whether the species is established or not.

Eastern Africa: It is present in the northern part of the Lake Turkana basin (Seegers et al. 2003).

Northern Africa: It is present but rare in Lake Nasser (also known as Lake Nubia)

Northeast Africa: This species is found in the Ghazal and Jebel systems, White Nile, and Nile to Lake Nasser, Sudan. It also occurs in the Baro River, Ethiopia.

Western Africa: Gymnarchus niloticus occurs in the basins of the rivers Gambia, Senegal, Niger, Volta, Ouémé and Chad.
Countries occurrence:
Benin; Burkina Faso; Cameroon; Central African Republic; Chad; Côte d'Ivoire; Egypt; Ethiopia; Ghana; Kenya; Mali; Mauritania; Niger; Nigeria; Senegal; South Sudan; Sudan; Togo
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:No information available.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Gymnarchus niloticus is a demersal, potamodromous species. Following flooding of the river banks (Gambia river) this species builds large elliptical floating nests in densely vegetated swamps at depths of about 1-1.5 m. Here the eggs are laid and later guarded by one of the parents. Distinct pairing. It lays about 1000 'amber-like' eggs and the larvae hatch after 5 days (Budgett 1901). It feeds on crustaceans, insects, snails, frogs and fish (Bailey 1994). During the day it hides in holes or close to the roots of water plants. This species possesses an electric organ that extends along almost the entire trunk to the tip of the tail (Bennet 1971), and is also equipped with ampullary receptors and two types of tuberous receptors for electroreception (Szabo 1974). It showed increased electric organ discharge (EOD) rate by 50-60 Hz between 21 and 31°C (Lissmann 1958). Gymnarchus niloticus breeds in well-vegetated, marginal areas of swamps and rivers, where a large, floating nest, about 1 m in diameter is constructed.
Movement patterns:Full Migrant

Use and Trade [top]

Use and Trade: This species is harvested for human consumption.

Threats [top]

Major Threat(s): This is a commercially important species in central Africa. In northern Africa, dams, water pollution (agriculture, domestic and commercial/industrial), groundwater extraction and drought pose possible threats. Deforestation and drought are local threats in western Africa.

Conservation Actions [top]

Conservation Actions: None known. More research is needed into this species population numbers and range, biology and ecology, habitat status and threats, as well as monitoring and potential conservation measures.

Citation: Azeroual, A., Entsua-Mensah, M., Getahun, A., Lalèyè, P., Moelants, T. & Vreven, E. 2010. Gymnarchus niloticus. The IUCN Red List of Threatened Species 2010: e.T181688A7706153. . Downloaded on 24 June 2018.
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