In terms of aquatic life, the Congo River Basin has a very high species richness, and among the highest known concentrations of endemics. , almost 800 fish species have been recorded from the Congo River Basin (not counting Lake Tanganyika, which is connected but ecologically very different), and large sections remain virtually unstudied. For example, the section in Salonga National Park, which is about the size of Belgium, had still not been sampled at all in 2006. New fish species are scientifically described with some regularity from the Congo River Basin and many undescribed species are known. The Congo has by far the highest diversity of any African river system; in comparison, the next richest are the Niger, Volta and Nile with about 240, 140 and 130 fish species, respectively. Due to this and the great ecological differences between the regions in the Congo basin —including habitats such as river rapids, deep rivers, streams, swamps and lakes— 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 below the surface, "Heterochromis multidens", which is 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.