Nam Xuan Lac Species and Habitat Conservation Area has highbiodiversity potential with many precious, rare, and endangered plant and animalspecies. However, the diversity of fish species in this reserve area has been limitedinformation until now. In order to provide information on the species compositionand distribution of fishes in the study site, two surveys were conducted in July andDecember 2021 at 11 stations (altitude from 118 m to 760 m) of the Lo and ThaiBinh river basins. Based on morphological characteristics, this study reported thefirst list of species composition of the Nature Reserve, with 22 species from 20genera, 16 families, and 7 orders. Of which, Cypriniformes was the most diverseorder, consisting of 6 families, 10 genera and 11 species, and Cyprinidae was themost dominant family (3 genera, 4 species). Besides, the present study also updatedand added two new records for the Red River ichthyofauna, two species listed inthe IUCN Red List and three species in the Government's Decree 26/2019/NĐ-CP.Of the 22 species collected, Neolissochilus benasi has the widest distribution rangein the study area. The number of species collected at sampling sites ranged from 2to 17 species. The present results are important data for the exploitation,conservation, and sustainable development of local fish resourcesNam Xuan Lac Species and Habitat Conservation Area has highbiodiversity potential with many precious, rare, and endangered plant and animalspecies. However, the diversity of fish species in this reserve area has been limitedinformation until now. In order to provide information on the species compositionand distribution of fishes in the study site, two surveys were conducted in July andDecember 2021 at 11 stations (altitude from 118 m to 760 m) of the Lo and ThaiBinh river basins. Based on morphological characteristics, this study reported thefirst list of species composition of the Nature Reserve, with 22 species from 20genera, 16 families, and 7 orders. Of which, Cypriniformes was the most diverseorder, consisting of 6 families, 10 genera and 11 species, and Cyprinidae was themost dominant family (3 genera, 4 species). Besides, the present study also updatedand added two new records for the Red River ichthyofauna, two species listed inthe IUCN Red List and three species in the Government's Decree 26/2019/NĐ-CP.Of the 22 species collected, Neolissochilus benasi has the widest distribution rangein the study area. The number of species collected at sampling sites ranged from 2to 17 species. The present results are important data for the exploitation,conservation, and sustainable development of local fish resources