Comparative Study on the Feeding Habits of Two Endemic and Sympatric Fish Species Capoeta tinca (Teleostei: Cyprinidae) and Chondrostoma angorense (Teleostei: Leuciscidae) in a River Ecosystem

The Devrez River has a diverse ichthyofauna, hosting nine endemic species. Gut contents of Capoeta tinca and Chondrostoma angorense were investigated monthly between April 2020 and March 2021 from the Devrez River in northern Türkiye. This study represents pioneering research on the feeding biology of these two endemic and economically important fish species. Dietary shifts were observed in both species across different ontogenetic stages and seasons. These fish, primarily feeding on river periphyton, consumed a diet comprising algae, particularly Chlorophyta, Charophyta, and Bacillariophyta, along with plant detritus. When compared to C. tinca, the relatively short gut length in C. angorense suggested its omnivorous nature; however, its consumption of plant-derived food items (algae and plant detritus) (97.3% in biovolume) was significantly higher than its consumption of animal-derived food (2.5%). The gut content analyses in terms of niche breadth indicate that C. tinca and C. angorense were specialized feeders in the Devrez River. The overlap in the diet appeared mostly in respect of algal food items which might lead to food competition between these fish species in case of limited food resources. This study aimed to contribute to the conservation and protection of two endemic fish species by addressing knowledge gaps related to their feeding patterns and trophic relationships.