We assessed the fish diversity of the Ogooue and Sebe rivers in and around the Rapids of Mboungou Badouma and Doume Ramsar site in Gabon. The ichthyofauna of this region has not been extensively sampled in over 150 years, yet encompasses one the most important type localities for fishes in Central Africa. We sampled a total of 31 sites and collected nearly 3000 fish specimens representing 97 species. Nine species appeared to be new to science, and one catalyzed the recent description of a new genus of mormyrid fishes. Keywords Africa, assemblages, fishes, freshwater, Ogooue, tropics, conservation.