, belonging to the family , are important economic fish species in the Lyusi fishing ground. With the rapid improvement of fishing power and production efficiency, coastal fisheries generally suffer from different degrees of overfishing, and the resources of also suffer from a continuous decline. The purpose of this paper is to provide a reference for the rational development and utilization of resources by analyzing their fatty acid composition, nutritional value, feeding habits, and dietary changes. The fatty acid composition of 46 individuals, collected from the Lyusi fishing ground during autumn 2018, was measured, and a dietary analysis was performed, based on the fatty acid labeling method. The results showed that fatty acid content of (21.77 mg/g); their SFA contents were similar (36.00%); the MUFA content of (15.92%), and the PUFA content of C. lucidus (47.91%). PUFA/SFA and n-3/n-6 of were higher than those found in common aquatic fish. The n-3/n-6 of P<0.05), whereas the PUFA/SFA of P<0.01). The characteristic fatty acids C18:2n6c and C20:5n3 (EPA) of P<0.05) and DHA/EPA had a significantly positive correlation with body length ( had a significantly negative correlation with body length ( had a higher herbivorous diet when the body length was less than 70 mm (<0.05), and a significant decrease in herbivorous diet when the body length was greater than or equal to 120 mm ( had a higher herbivorous diet when the body length was less than 70 mm (<0.05), and a significant decrease in herbivorous diet when the body length was greater than or equal to 100 mm ( (2.6-5.9) partially overlapped with (2.6-3.3). The research indicated that the nutritional values of were very high; the larger individuals' fish oil of had a higher nutritional value, and the smaller individuals of were more beneficial to cardiovascular health. Their trophic levels were partially overlapping, and their feeding habits were similar. As the body length increased, the herbivorous diet decreased and carnivorous diet increased, and the body length was similar when the diet changed. Therefore, they may have a certain niche overlap and food competition.