The dietary protein to energy ratio, in fish diets, is of great importance. Levels of dietary protein and energy, not only influence the growth and body composition, but also digestive enzymes activities and plasma metabolites in various fishes and increasing the protein level of the diet does not result in better protein utilization. Providing adequate energy through dietary lipids can minimize the use of more costly protein as an energy source. The objective of the present study was to study the effect of varying dietary protein, lipid and carbohydrate contents on the growth and feed performance, nutrient and energy utilization, digestibility, body composition and organ indices of Cyprinus carpio communis fingerlings in order to determine the feed formulation with optimum P/E ratio which would reduce the FCR value and make production of Common carp economical. To further understand the metabolic effects of dietary nutrients, variations in acid and alkaline phosphatase enzyme activities were also studied. The present work will be helpful for the fish nutrition scientists and the fish nutrition research students.