**5. Conclusions**

The observations in this study confirm that *P. parva* has diverse diet preferences. Therefore, the topmouth gudgeon should be considered a serious threat to the diversity of food chain in Lake Egirdir since the fish consumes all kinds of organisms in the chain. In addition, it has a potential to carry a variety of diseases. It also be noted that the fish have abilities to produce eggs in large diameters and grow rapidly in a dense population size in a short time. Sexual dimorphism and nest protection behavior are the other advantages of the fish to become a dominant fish population in the lake. Our study is expected to contribute to better knowledge of diet composition of topmouth gudgeon in Lake Eğirdir for future researches. We hope that future researchers can estimate the possible damages on the biomass and species composition of zooplankton in relation to their considerable consumption by the increasing population of *P. parva* in the lake. Finally, it is important to point out that invasive non-native fish species should be kept away from natural ecosystems since they constitute a great threat for native fish species for food and breeding grounds.
