The inland fisheries sector is central for subsistence in many regions worldwide. The exploitation of fish resources is expected to increase along with the growing human population, with underlying conservation issues in regions with high biodiversity value. The small fishery of the Maroni River, French Guiana, is a hotspot of biodiversity and endemism where resource depletion is suspected. We surveyed 754 boat landings in seven villages located in the upper half of the watershed, representing > 6300 fish during the study period (November 2013 - September 2014). Fishers used canoes with outboard engines almost exclusively (75 %) and fished within 32 km of their villages. Most fish were caught in trammel nets (81 %); the 20 most-landed species represented more than 87 % of catches. Depending on the village, daily catches and biomass averaged 6–14 fish and 1.7−13 kg per boat landing, respectively. Seven control sites located outside of the fishing grounds were fished to identify potential differences in catch per unit effort and fish size. Per 100 m2 of trammel net, mean catches ranged from 4 to 13 and 8–29 fish in the villages and control sites, respectively, while fish biomass ranged from 0.9 to 4 and 3.2−7 kg in villages and control sites, respectively. For all species combined, fish caught at control sites were bigger than those landed in villages. This difference was significant for nine of the most-landed species. Differences in fishing techniques and fish catches between villages illustrated the gradual disappearance of the ancestral subsistence fishing. Our results support indications that the fish community in the upper Maroni River is harvested intensively, address the issue of sustainability of the fishery there, and call attention to the need to conserve the river’s remarkable biodiversity.