Deposit-feeding gastropods provide integral links between benthic productivity and higher trophic levels in a variety of aquatic environments. At high population densities these snails can exert a significant grazing impact on available microphytobenthos (MPB). Here we provide the first report on the potential ingestion rates and feeding impact of the freshwater thiarid Melanoides tuberculata. This species consists of a variety of distinct morphs that have been introduced and become invasive in many areas in the New World. We used an in situ fluorometric approach to elucidate the feeding dynamics of three M. tuberculata populations from different habitat types. Daily ingestion rates, potential daily feeding impact and per capita resource availability were calculated based on snail density and MPB biomass. The highest maximum potential ingestion rate was estimated when snails occurred at the lowest population density, where per capita resource availability was highest. Feeding impact, in terms of potential daily consumption of MPB, varied depending on gut passage time and pigment consumption/digestion efficiency. Overall, the feeding dynamics of M. tuberculata were significantly different between populations. The variation in traits related to feeding dynamics, whether plastic or adaptive, contributes to the generalist nature of M. tuberculata. It is expected that these traits facilitate invasion success, as the species is able to inhabit and persist in a range of aquatic environments under different levels of resource availability.