Pseudorasbora parva (Temminck and Schlegel, 1846) is widely distributed in rivers and lakes of Turkey owing to accidental introductions. Turkey is rich in biodiversity of freshwater fish and has a high level of endemicity of native ichthyofauna, which is vulnerable to such introductions. The Gelingullu Reservoir located on the Kizilirmak drainage in Central Anatolia has rich ichthyofauna with native and introduced fish species, including endemic species. The contents of the foregut of P. parva samples collected between Summer 2003 and Summer 2005 were examined. Seasonal and ontogenetic changes in feeding intensity were determined. P. parva mainly feeds on zooplankton such as Cladocera, Copepoda, and Rotifera. Members of the Bacillariophyta and Cyanobacteria were identified in high proportions in the foregut contents of P. parva particularly during summer. The feeding traits of this invasive fish may have an influence on the establishment of a successful population in Gelingullu reservoir.