Abstract: Diets containing different level of crude protein and essential amino acids index(EAAI)were fed respectively to allogynogenetic silver crucian carp. Each diet was fed to three aquaria and there were 10% group、20% group、30% group、40% group and 50% group in accordance with the protein content of diets fed the fish. The analysis and determination were carried out respectively in six weeks later and fourteen weeks later. Results indicated that the weight gain rate increased with the protein level elevating in six weeks later, While the 40% group is the highest in fourteen weeks later. There were no significant difference among 30% group、40% group and 50% group, but 10% group and 20% group decreased markedly. Protein efficiency rate(PER)of 10% group and 50% group in fourteen weeks later depressed significantly than that in six weeks later, and that of 30% group is the highest in fourteen weeks later. Both weight gain rate and PER depressed with the EAAI decreasing. There were no significant difference in immunological activities between 20% group and 30% group, with the 20% group is the highest. Immunological activities depressed with the EAAI decreasing too. All those indicate that fish in great weight gain rate were not often with the strongest immunological activities. Further more, there were marked relation between immunological activity and body lipid content.(P＜0.05)