Response of the Diet Composition of Carassius auratus to Water Quality in Dianchi Lake, China

ABSTRACT

Understanding the relationship between the diet composition of fish and water quality is significant for assessing fish responses to habitat changes. However, due to the complexity and diversity of both fish feeding and water quality, the relationship between the diet composition of fish and water quality is not fully understood to date. This study investigated the diet composition of Carassius auratus in Dianchi Lake, China, and their relationship with water quality. Fish and water samples were collected from three sites representing the northern, central, and southern regions of Dianchi Lake, with six fish per site and 18 individuals in total. Gut content analysis showed that the diet composition of C. auratus was mainly Planktothrix , Microcystis , Microsporidium , Brachionus , Cyprinus , and Chanodichthys , and their diet composition was clearly different in space. The correlation results showed that Planktothrix in the gut of C. auratus showed a strong positive correlation with eukaryotic algae, cladocerans, and dissolved oxygen in the water. Microcystis in the gut of C. auratus was positively correlated with temperature and total nitrogen in the water. Brachionus in the gut of C. auratus showed strong negative correlation with water borne cyanobacteria and strong positive correlations with eukaryotic algae and dissolved oxygen. Cyprinus in the gut of C. auratus had a positive correlation with rotifers in the water. Overall, these findings suggest that the diet composition of C. auratus was associated with the abundance of plankton, their availability in the aquatic environment, and variations in the physicochemical properties of the water column. The study's findings provide C. auratus a fresh outlook on how to adjust to changes in lake habitat.