Situated along the Altantic coastline of the DR Congo, the Marine Mangrove Park (MMP), covering an area of ±65.800 ha, includes: (1) a Core Zone consisting of islands covered by the typical salt resistant mangrove trees and shrubs at the mouth of the Congo River; and (2) a Buffer Zone consisting of a coastal strip along the ocean and a humid savannah strip more upstream along the Congo river. The coastal strip is intersected by two small coastal river basins and the wet savannah by eight small Congo River tributaries. A compilation of the collection data from the Royal Museum for Central Africa resulted in a total of 166 nominal species distributed over 56 families. Most species rich are the Cichlidae (13), Carangidae (12), Gobiidae (8), Anabantidae (7), Mormyridae (7), Mugilidae (7), Carcharhinidae (6), Clariidae (6), Claroteidae (6) and Clupeidae (5). In addition, 24 species are known from the vicinity of MMP, but have not yet been collected within its borders. Except for the Tonde and the Luibi, none of the rivers have been explored and many small pools still remain unexplored as well. Despites these sampling gaps, preliminary results already highlight a species rich and characteristic estuarine and mangrove-associated fish fauna composed of typical marine, brackish as well as freshwater species. Although fishing is artisanal, sustainable harvesting is threatened by the use of mosquito nets. In addition, water pollution due to oil exploration and exploitation and the activities of refineries becomes worrying. Therefore, the aims set by the present study are, not only, (1) to document the fish species diversity of the MMP, and (2) to study their ecology at some target localities; but also to (3) identify the major fishing areas and targeted species in order to develop conservation and sustainable management guidelines for its fish fauna.