<p>This study evaluated filtration, ingestion, and food selectivity of the bivalves <i>Diplodon parodizi</i> (native) and <i>Corbicula fluminea</i> (invasive). We hypothesized that these bivalves differ in filtration and ingestion rates as well as in food selectivity, showing distinct phytoplankton preferences. To test this, both bivalves were exposed to a mixed phytoplankton community composed of diatoms, chlorophytes, cyanobacteria, charophytes, rhodophytes, dinoflagellates, and xanthophytes in aquaria for two hours. Afterward, the bivalves were removed, and the remaining particles were filtered to estimate filtration, ingestion and food selectivity. No significant differences in filtration rates were found between the two species (<i>P</i> = 0.11). A significant difference in diatom ingestion rates was observed between the bivalves, with <i>D. parodizi</i> ingesting more cells than <i>C. fluminea</i> (<i>P</i> = 0.0229). Food selectivity analysis showed that <i>D. parodizi</i> had stronger negative selection for cyanobacteria, dinoflagellates, xanthophytes, and diatoms, while <i>C. fluminea</i> showed negative selection only for dinoflagellates and diatoms. Although both species were able to feed on all phytoplankton groups, the broader avoidance by the native species may suggest a disadvantage when sharing resources with invaders. These findings contribute to a better understanding of dietary differences between native and invasive bivalves and their potential ecological impacts.</p>