''Acapoeta tanganicae'', or the mbaraga, is a species of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

in the family

Cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest verte ...

. The genus ''Acopoeta'' is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

and is currently regarded as ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'', as its placement within the large and varied assemblage of Cyprinidae is uncertain. ''Acapoeta tanganicae'' is endemic to

Lake Tanganyika Lake Tanganyika () is an African Great Lake. It is the second-oldest freshwater lake in the world, the second-largest by volume, and the second-deepest, in all cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. ...

and the

Rusizi River Rusizi may refer to: * Rusizi River, a river which flows between Lakes Kivu and Tanganyika, in Rwanda, Burundi and the DRC * Rusizi National Park, a park based on the river Rusizi near Bujumbura, Burundi * Rusizi (district), a district in Western P ...

and occurs in

Burundi Burundi (, ), officially the Republic of Burundi ( rn, Repuburika y’Uburundi ; Swahili language, Swahili: ''Jamuhuri ya Burundi''; French language, French: ''République du Burundi'' ), is a landlocked country in the Great Rift Valley at the ...

Democratic Republic of the Congo The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...

, and

Zambia Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most cent ...

. In 2012, this species was caught in the

Lake Rukwa Lake Rukwa is an endorheic lake located the Rukwa Valley of Rukwa Region, Songwe Region and Katavi Region in southwestern Tanzania. The lake is the third largest inland body of water in the country. Geography The alkaline Lake Rukwa lies midway ...

catchment, and it has been suggested that this is indicative that the catchments of Lake Tanganyika and Lake Rukwa were connected at some point in the past. It was considered that the most parsimonious explanation for its presence was that its low abundance meant it had been previously overlooked as a member of the Lake Rukwa

ichthyofauna Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

rather than deliberate introduction. Its natural

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s are

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

s, freshwater

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s, and inland deltas over rock substrates. It feeds on aufwuchs as well as a variety of food collected from rocky river or lake beds including insects, ostracods, diatoms and worms. It is threatened by

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

caused by increased turbidity of the water due to deforestation increasing sediment runoff in the catchments of the lake's tributary rivers. Overfishing may also be a threat, although the species is still common and can be present in large shoals, and there is no data to support a decline in the stock. It can grow up to in total length. This species is distinguished from similar species of African cyprinids by having a horny rim to its lower lip and a larger number of

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

scales, ''Acapoeta'' having 62–72 lateral line scales compared to 21–44 in ''

Labeobarbus ''Labeobarbus'' is a mid-sized ray-finned fish genus in the family Cyprinidae. Its species are widely distributed throughout eastern Africa and especially southern Africa, but also in Lake Tana in Ethiopia. A common name, in particular for th ...

'' species.

References

{{Taxonbar, from=Q11904060, from2=Q2698663 Cyprinid fish of Africa Fish of Burundi Fish of the Democratic Republic of the Congo Freshwater fish of Tanzania Fish of Zambia Fish of Lake Tanganyika Taxa named by Theodore Dru Alison Cockerell Monotypic fish genera Taxonomy articles created by Polbot