Heterotis niloticus 

Scope: Global & Pan-Africa
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Osteoglossiformes Arapaimidae

Scientific Name: Heterotis niloticus (Cuvier, 1829)
Regional Assessments:
Common Name(s):
English Heterotis, African Arowana, African Bonytongue, Bony Tongue, No name, Stoneside
French Poisson sans nom
Clupisudis niloticus (Cuvier, 1829)
Heterotis adansoni Valenciennes, 1847
Heterotis adansonii (Cuvier, 1829)
Heterotis ehrenbergii Valenciennes, 1847
Heterotis nilotica (Cuvier, 1829)
Sudis adansonii Cuvier, 1829
Sudis nilotica Cuvier, 1829
Sudis niloticus Cuvier, 1829
Sudis niloticus Rüppell, 1829

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2010
Date Assessed: 2009-05-01
Assessor(s): Akinyi, E., Azeroual, A., Entsua-Mensah, M., Getahun, A., Lalèyè, P. & Moelants, T.
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 eastern, north eastern and western Africa. In central Africa region it has been assessed as Not Applicable as the species has been widely introduced within the area, for aquaculture purposes. In north Africa this species is now Regionally Extinct. It used to be caught from upper Egyptian Nile. The Aswan High Dam is believed to be the reason for extinction within the region.

Geographic Range [top]

Range Description:Heterotis niloticus is natural distributed in savannah rivers of the Nilo-Sudanese region from Ethiopia to Senegal. It is also naturally distributed in the Chad basin and Lake Turkana. The species current distribution is now far more wide-spread as a result of man-made introductions.

Central Africa: The species has been widely introduced in the Lower Guinea area, for aquaculture purposes. The species was introduced from Fort-Lamy, Chad, or Northern Cameroon to Southern Cameroon (swamps of the Nyong River basin, Cameroon). It was used for the development of aquaculture in the fish culture station of Melen near Yaoundé (1955), in Bertoua (1957) and in Abong-Mbang (1958). From 1968 onwards it was also found in the Lower Sanaga River basin. According to Depierre and Vivien (1977), this was probably due to colonization originating from the Lower Nyong River basin and this through the mangroves during the high waters. In the 1950’s it was also introduced from Cameroon to the Lower Ogowe River basin, in the neighbourhood of Lambaréné, Gabon, and from Cameroon to Congo. According to FAO (2005) it was reintroduced to Congo in 1960, with Sudan mentioned as country of origin. Olaosebikan and Raji (1998) report the introduction of the species in the Cross River basin, Nigeria.

Eastern Africa: It is present in Lake Turkana.

Northern Africa:This species used to be caught from This species is known from upper Egyptian Nile, but is now Regionally Extinct.

Northeast Africa: It is found in the Ghazal and Jebel systems, White Nile to Khartoum, Sudan, as well as Baro River, Ethiopia

Western Africa: In the case of this species, a distinction must be made between the present area of occurrence resulting from man-made introductions, and its original, natural geographical distribution area. Original (natural) distribution: all basins of the Nilo-Sudanese region: rivers Senegal, Gambia, Volta, Niger, Chad. Areas of successful introduction of the species: in the area considered, artificial reservoirs of Côte d'Ivoire and Cross river.
Countries occurrence:
Benin; Burkina Faso; Cameroon; Chad; Côte d'Ivoire; Egypt; Ethiopia; Gambia; Ghana; Guinea; Guinea-Bissau; Kenya; Mali; Niger; Nigeria; Senegal; South Sudan; Sudan
Central African Republic; Congo; Congo, The Democratic Republic of the; Gabon; Madagascar; Togo
FAO Marine Fishing Areas:
Atlantic – eastern central
Additional data:
Upper depth limit (metres):1
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:No data on population trends.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Heterotis niloticus is a pelagic species. It occurs in shallow water where it feeds on invertebrates, copepods and chironomids (Reed 1967). Young are found in swampy places among aquatic vegetation (Moreau 1982, Dankwa et al. 1999); adults live in the open water of rivers and lakes, where they can be found in the pelagic zone as well as the littoral zone (Moreau 1982). Its auxiliary branchial air breathing organs enable it to survive in de-oxygenated 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 (Welcomme 1988, Daget and d'Aubenton 1956). Escapees from ponds into the wild resulted in established populations, which form the basis for fisheries (Welcomme 1988). This species is considered as a mud-feeder (Hickley and Bailey 1987), but in West Africa also as a phytoplankton feeder (Holden and Reed 1972, Olaosebikan and Raji 1998). It feeds mostly on plankton, being the only plankton-feeder of the Osteoglossidae (Reed et al. 1967). It has a suprabranchial organ which has a sensory function, but also a mechanic function in concentrating the little food particles (Daget and Durand 1981, d’Aubenton 1955). During breeding, it creates a circular nest in swamps (Reed et al. 1967, Balon 1975, Budgett 1901). The young leave the nest after a few days and are guarded by the male (Balon 1975). Heterotis niloticus breeds in the wet season in swamps and floodplains (Bailey 1994). It builds a circular nest about 1 m in diameter and 20 to 60 cm deep (Balon 1975), similar to a lagoon. The rim of the nest is a high wall formed out of plant chunks, about 15-20 cm thick and projecting above the water surface; the bottom is a clean platform of clay or mud (Balon 1975). After the spawning act the fish leave by way of a hole in the wall, through which, 5 days later, the young leave the nest and are guarded by the male (Balon 1975). Young possess external gills.

Use and Trade [top]

Use and Trade: 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.

Threats [top]

Major Threat(s): More information is needed. It is reported as a commercially important fish in central Africa, but not eastern Africa. Threats in other regions are unknown.

Conservation Actions [top]

Conservation Actions: None known. Population trends need monitoring.

Citation: Akinyi, E., Azeroual, A., Entsua-Mensah, M., Getahun, A., Lalèyè, P. & Moelants, T. 2010. Heterotis niloticus. The IUCN Red List of Threatened Species 2010: e.T182580A7920022. . Downloaded on 26 September 2018.
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