Stomatepia mongo, the Mongo, is a species of cichlid endemic to Lake Barombi Mbo in western Cameroon. It can reach a length of 13 centimetres (5.1 in) SL. This species has a stable population and the lake is protected faithfully by the Barombi people who live around the perimeter of the lake. Small, irregular emissions of carbon dioxide (CO2) from the lake's bottom has killed fish when it occurs, but not enough to threaten the overall ecological balance of this lake,(compare Lake Nyos), as studies indicate that Barombo Mbo lacks excess amounts of this gas. Even compared to other cichlids that are endemic Lake Barombi Mbo, Stomatepia mongo is a very rare species.
Very little is known about its behavior, but it has been seen swimming near the bottom, apparently looking for small prey items in the detritus or sand. It sometimes occurs in small groups.