Lake Maï Ndombe

Lake Mai-Ndombe
seen from space (false color)
Location	Bandundu Province
Coordinates	2°00′S 18°20′E / 2°S 18.33°E / -2; 18.33Coordinates: 2°00′S 18°20′E / 2°S 18.33°E / -2; 18.33
Primary outflows	Fimi River
Basin countries	Democratic Republic of the Congo
Surface area	890 sq mi (2,300 km2)
Average depth	5 m (16 ft)
Max. depth	10 m (33 ft)

Lake Mai-Ndombe (French: Lac Mai-Ndombe) is a large freshwater lake in the Mai-Ndombe District of the Bandundu Province in western Democratic Republic of the Congo. The lake is within the Tumba-Ngiri-Maindombe area, the largest Wetland of International Importance recognized by the Ramsar Convention in the world.

The lake drains to the south through the Fimi River into the Kwah and Congo Rivers. Known until 1972 as Lake Leopold (after the Leopold II, King of the Belgians, also known as the 'Butcher of Congo'). Mai-Ndombe means “black water” in Lingala. The lake is of irregular shape and ranges in depth from only 5 meters (mean) to 10 meters (maximum). Covering approximately 890 square miles (2,300 square km), it is known to double or triple in size during the rainy season. Its waters are oxygenated throughout their depth and the pH ranges from 4.2 to 5.5. Low, forested shores surround it with dense, humid equatorial rainforest prevailing to the north and a mosaic of forest and savanna to the south.

The fish of Lake Mai-Ndombe, although presumed to be similar to those of Lake Tumba, have been poorly documented. Since initial surveys from 1909-1916 by George Albert Boulenger, the lake has been a site for the continual discovery of new species. In 1984 a new species of cichlid, Nanochromis transvestitus, named for the fact that it exhibits reverse sexual dichromatism, was discovered in the lake. In 2006 a new species of cichlid, Nanochromis wickleri, was discovered, and in 2008, yet another new species, Chrysichthys praecox, was documented.