In Guinea, water resources are under anthropogenic pressure. Changes in water quality can impact the composition of aquatic fauna. To date this fauna is practically unknown in the Niger River in Guinea. Our research was carried out on a 10 km route from the river to Faranah town centre. The general objective is to assess the richness and distribution of macroinvertebrates. Five stations were sampled during three hydrological regimes: Periods of low water, rising water and recession. Changes in composition, abundance and richness were determined by Kruskal-Wallis analysis of variance. The Equitability Index was used to assess the distribution of different taxa in the sampled stations. The percentage of occurrence is used to determine the frequency of a taxon in a station. Diversity was assessed by the Shannon index. These indices were calculated considering the family as a taxonomic level. At the end of the inventory, 60 families were identified divided into 14 orders for 5 classes (insects, lamellibranchs, gastropods, crustaceans and annelids). This population is dominated by insects 57%. The faunal composition corresponds to the richness of African fresh waters. Depending on the hydrological regimes, 85% of the species collected are constant while for all the stations it is 88% which are fixed. The values of the Shannon ˃2 and equitability indices close to 1 reflect the presence of a very rich, diverse and stable benthic fauna.