Pollimyrus nigricans 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Osteoglossiformes Mormyridae

Scientific Name: Pollimyrus nigricans (Boulenger, 1906)
Common Name(s):
English Dark Stonebasher
Taxonomic Notes: Also reported as Marcusenius nigricans (antiquated binomen) (Seegers et al. 2003).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2015-12-21
Assessor(s): FishBase team RMCA & Geelhand, D.
Reviewer(s): Kishe, M., Natugonza, V., Nyingi, D. & Snoeks, J.
Contributor(s): Musschoot, T., Boden, G. & Twongo, T.K.
Facilitator/Compiler(s): Darwall, W.R.T.
Pollimyrus nigricans is known from the Lake Victoria, Akagera, Lake Tanganyika, Rusizi and Malagarazi basins. It is rarely encountered although it has a wide distribution. Although this stonebasher has suffered local declines in the Lake Victoria basin, no major, widespread threats have been identified that impact the whole population. This mormyrid is therefore listed as Least Concern.

Geographic Range [top]

Range Description:This species is known from the Lake Victoria basin in Uganda (Greenwood 1966), Kenya (Seegers et al. 2003) and Tanzania (Eccles 1992). It also occurs in Lakes Nabugabo and Kyoga, the Kiruni River (Semuliki valley) (Greenwood 1966), the Lake Tanganyika basin (Worthington and Ricardo 1936) and the Akagera system in Rwanda (De Vos et al. 2001) and Burundi (De Vos 1991). Pollimyrus nigricans is reported from the Malagarazi River basin in Tanzania (Eccles 1992) and Burundi (Banyankimbona et al. 2012), and from the Rusizi River basin in the Democratic Republic of the Congo (Marlier 1953) and Burundi (Banyankimbona et al. 2012).
Countries occurrence:
Burundi; Congo, The Democratic Republic of the; Kenya; Rwanda; Tanzania, United Republic of; Uganda
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:It is rarely encountered (Greenwood 1966) but may be locally very abundant. Otherwise no information is available on the population size and population trend of this species.
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Pollimyrus nigricans favours shallow, soft bottom habitats near fringing vegetation such as papyrus and Vossia (Okedi 1971). It feeds on aquatic insects, particularly chironomid larvae (Corbet 1961), Caridina and caenid larvae (Okedi 1971). Algae and plankton have also been found in the stomach of this species (Copley 1958). A male/female ratio of 1:10.5 has been noted in this species (Okedi 1969) and it is able to live in water deficient in oxygen (Okedi 1971). Pollimyrus nigricans has a low fecundity (Okedi 1970), but breeds continuously throughout the year with obvious peaks during the rains (Okedi 1969). It migrates up the rivers to spawn in temporary pools and streams (Okedi 1969). The maximum size is 10.0 cm SL (Eccles 1992).
Movement patterns:Full Migrant

Use and Trade [top]

Use and Trade: Incidental catch in artisanal fisheries.

Threats [top]

Major Threat(s): In the Lake Victoria basin, threats include water turbidity and siltation as a consequence of erosion and farming expansion on the watersheds and floodplains, loss of papyrus swamps and other vegetated wetlands due to agriculture expansion, irrigation, eutrophication, loss of riverine migratory routes and fishing pressure. Introduced fish species have possibly contributed to the decline of the species and in Lake Nabugabo P. nigricans disappeared coincident with introduction of Nile Perch (Chapman and Hulen 2001, Chapman et al. 2003). In the Malagarazi River basin, sedimentation and increased use of agrochemicals (pesticides and fertilizers) as a result of agricultural expansion, and pollution from future mining activities (nickel, gold) are threats (West 2001).

Conservation Actions [top]

Conservation Actions: No conservation actions are known for this species. Population and habitat trends should be monitored in the Lake Victoria region.

Citation: FishBase team RMCA & Geelhand, D. 2016. Pollimyrus nigricans. The IUCN Red List of Threatened Species 2016: e.T60350A47184399. . Downloaded on 24 June 2018.
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