Influence of cage fish farming on diet composition of Sardela (Triportheus nematurus (Kner, 1858)) in a Neotropical reservoir.

Cage fish farming promotes the input of organic matter into the surrounding aquatic environment, which can alter the availability of food resources and consequently change the diet of wild fish. Thus, gathering information about cage fish farming influences on the aquatic environment is important. We aimed to evaluate the effects of cage fish farming on the trophic ecology of the omnivorous and non-native fish Triportheus nematurus. We collected individuals in areas with (CF) and without (CT) the influence of cage fish farms in April and July 2019, to analyze the stomach contents to determine the diet composition of the individuals. The diet composition and the trophic guild were different between the CT and CF groups. However, the average trophic niche breadth did not differ between groups. Triportheus nematurus did not directly consume the organic matter coming from the cages, such as feed. Still, we suggest that the differences occurred due to changes in the availability of food resources promoted by cage fish farms and the attractive potential of the cultivation cages. In short, these results can help understand the implications of this cultivation system in the aquatic environment, contributing with new information and expanding already described data.