A study was conducted at Lake Ndjale to identify the fish that inhabit this aquatic ecosystem. This study contributes on the one hand to the knowledge of the fish fauna and to preserve in order to consider the introduction of the interesting species in pisciculture to improve the nutritional state of the population and its income. We thought that Lake Ndjale would overflow a relatively diversified ichthyofauna that would be poorly or poorly known. At the end of this study, we obtained the following results: - The fish inventory covered a collection of 648 fish divided into 9 families, 11 genera and 12 species that 9 families and 11 genera of the fish were listed. The families of Cichlidae and Mormyridae each have two genera and each genus bears one species. The families of Hepsetidae, Bagridae, Citharinidae, Mochocidae, Distichodontidae and Notopteridae are single-species families with one species per genus; except the family of Alestidae which is also mono-genus but with two species. - The analysis of the relative index of fish communities in Lake Ndjale provides sufficient evidence that the Mochocidae family is the best represented. It has 508 specimens in all the samples ie 78.61% Synondotis, Chrysichthys nigrodigitatus (6.8%), Marcusenius sanagaensis (5.41%), Oreochromis niloticus (4.79%), Brycinus derheni (0.92%), Hemichromis fasciatus, Hepsetus odoe and Distochodu rostratus (0.61%), Gnathonemus peterssi, Xenomythus nigri and Citharinus latus are only 0.46%. Based on our results, our hypothesis is verified and confirmed.