Steatocranus masalamasoso, a new species of small rheophilic cichlid species, is described from the Masala Ma Soso Rapids on the Léfini River, Central Congo basin. It is distinguished from its congeners by the number of circumpeduncular scales (18-20 vs. 12-16). The construction of a hydroelectric dam on the Léfini River, located at about 3 km upstream of the type locality of S. masalamasoso and operational since 2009, resulted in the inundation of the Masala Ma Soso Rapids. Recent efforts to collect S. masalamasoso failed, suggesting that adverse downstream effects of the dam on the original habitat, may have led to the demise of the species.