Despite the long tradition of ichthyofaunal research in the Balkan Peninsula, there are still poorly investigated areas. Kosovo is one of the least investigated countries of the Balkan Peninsula in regard to fish fauna. In this study, we present the results of a fish fauna investigation in Badovc Lake and the Llap River. The fish fauna of Badovc Lake in central Kosovo was investigated at monthly intervals between June 2012 and December 2012. A total of 16 species belonging to 6 families, Cyprinidae, Cobitidae, Percidae, Siluridae, Esocidae, and Centrarhidae, were determined in this research area. The vast majority of species found belong to the family Cyprinidae (11), while all other families are represented by a single species. At 10 selected stations of the Llap River, 12 fish species were found. The family Cyprinidae is represented by 10 species, while 2 other families (Percidae and Salmonidae) are represented by a single species. The first preliminary checklist of fish species found in freshwater ecosystems belonging to the Black Sea basin in Kosovo is given and it contains 27 species. According to the IUCN criteria, 25 of the species found are in the category of Least Concern, and the 2 remaining species are in the category of Vulnerable species (Cyprinus caprio and Alburnoides bipunctatus). This investigation shows that the alien invasive pumpkinseed fish Lepomis gibbosus, which is reported here for the first time from Kosovo, is expanding its distribution area in the Balkan Peninsula. In this context, more detailed investigations are needed in this part of Kosovo in order to determine the diversity and number of fish populations.