Trophic niche overlap between native and non-native fishes in central Anatolian lakes, Türkiye.

The Central Anatolian region of Türkiye exhibits exceptionally high freshwater fish diversity and endemism and is increasingly exposed to the introduction of non-native taxa. We examined the diet composition, prey selectivity and interspecific dietary overlap among eight native and five non-native fish species across seven lakes in Central Anatolia. Fish were sampled using multimesh gill nets and fyke nets, and their stomach contents were identified. In addition, zooplankton and benthic macroinvertebrate communities were quantified to evaluate prey selectivity patterns. Aquatic insects were the main food sources (averaging 60%), followed by cladocerans (25%), for both native and non-native fish species. Horn's index indicated a high dietary overlap (>0.60) between several native and non-native species, suggesting substantial overlap in resource use and the potential for exploitative interactions. Native species generally exhibited more specialized diets, whereas non-native species tended to be generalists. Prey selectivity analysis revealed that both native and non-native species preferentially consumed aquatic insects over other available prey types, indicating shared reliance on benthic food resources. These findings suggest that non-native fishes may influence trophic structure and resource use patterns in freshwater ecosystems with high endemism. We emphasize the importance of region-specific monitoring and management strategies to mitigate the ecological impacts of non-native fishes and support the conservation of Türkiye's freshwater biodiversity.