This review is the first stocktake of the freshwater biodiversity in the transboundary Mara river basin of Kenya and Tanzania. Information was collated from available literature and acts as a baseline of the basin's freshwater biodiversity, its distribution and status. The Mara river basin is home to at least 473 freshwater species including at least 4 mammals, 88 waterbirds, 126 freshwater-associated birds, 4 reptiles, 20 amphibians, 40 fishes, 50 invertebrate species and 141 vascular plants. As many species are not yet identified or described, especially invertebrates and fishes, there could be hundreds more.
