<P> It is feared that these new hydroelectric dams could lead to the extinction of many of the fish species that are native to the river . </P> <P> The current course of the Congo River formed 1.5--2 million years BP, during the Pleistocene . </P> <P> The Congo's formation may have led to the allopatric speciation of the bonobo and the common chimpanzee from their most recent common ancestor . The bonobo is endemic to the humid forests in the region, as are other iconic species like the Allen's swamp monkey, dryas monkey, aquatic genet, okapi, and Congo peafowl . </P> <P> In terms of aquatic life, the Congo River Basin has a very high species richness, and among the highest known concentrations of endemics . Until now, almost 700 fish species have been recorded from the Congo River Basin, and large sections remain virtually unstudied . This is by far the highest diversity of any African river system (in comparison, the next richest are the Niger, Volta and Nile with about 210, 140 and 130 fish species, respectively). Due to this and the great ecological differences between the regions in the Congo basin, it is often divided into multiple ecoregions (instead of treating it as a single ecoregion). Among these ecoregions, the Lower Congo Rapids alone has more than 300 fish species, including approximately 80 endemics while the southwestern part (Kasai Basin) alone has more than 200 fish species, of which about a quarter are endemic . The dominant fish families--at least in parts of the river--are Cyprinidae (carp / cyprinids, such as Labeo simpsoni), Mormyridae (elephantfishes), Alestidae (African tetras), Mochokidae (squeaker catfishes), and Cichlidae (cichlids). Among the natives in the river is the huge, highly carnivorous giant tigerfish . Three of the more unusual endemics are the whitish (non-pigmented) and blind Lamprologus lethops, which is believed to live as deep as 160 metres (520 ft) below the surface, Heterochromis multidens, which appears to be more closely related to cichlids of the Americas than other African cichlids, and Caecobarbus geertsii, the only known cavefish in Central Africa . There are also numerous endemic frogs and snails . Several hydroelectric dams are planned on the river, and these may lead to the extinction of many of the endemics . </P>

Which river system flows through the largest rainforest in africa