In the absence of a proper definition based on comprehensive anatomical investigations, the genus FluviopupaPilsbry, 1911 has been used for hydrobioid gastropods from several continental regions and oceanic islands in the southwest and south Pacific. The type species F. pupoideaPilsbry, 1911 was the only hydrobioid gastropod known from Fiji to date. In this paper we provide descriptions of shell, operculum, radula and anatomy of 10 species of Fluviopupa from Fiji including the type species. This and seven other species occur on Viti Levu. The remaining two species were found on Vanua Levu. The high diversity is not surprising considering similar distribution and diversity patterns of spring and stream-dwelling hydrobioid gastropods in other parts of the world. Based on geology, geography and comparative anatomy, we hypothesize that the ancestor of the Fijian taxa was likely a freshwater species sharing a common ancestor with extant taxa in either New Caledonia or New Zealand. The islands of Vanuatu may have served as stepping stones.