Zinc (Zn) is an essential trace element in fish. It functions as a cofactor in several enzyme systems and isinvolved in many important physiological processes, including improved growth and development, immune function,and defense against free radicals. Signs of impaired growth, increased mortality, cataracts, short body dwarfism, andlow tissue Zn may occur in fish fed a Zn-deficient diet. In contrast, excessive dietary Zn can negatively affect the nutritionalstatus of other elements, such as iron, cadmium, and magnesium. Therefore, it is necessary to ensure minimaldietary levels to meet the requirement and be certain that levels do not exceed the maximal limits, which can affectgrowth and other responses in fish. Blunt snout bream (Megalobrama amblycephala) is in the Cyprinidae family, whichis one of the largest fish families in the world. Production of cyprinids reached about 0.71 million tons in 2011, which isthe seventh most freshwater-cultured fish species in China (Bureau of Fisheries of the Ministry of Agriculture , China,2012). The blunt snout bream has become an important and popular freshwater species. The dietary zinc requirementforblunt snout bream is reportedly 20–184 mg/kg. We conducted a 12-week growth experiment to quantify the optimumdietary Zn requirement of juvenile blunt snout bream and evaluated its effects on antioxidant responses in this species.Seven experimental diets were formulated to contain graded levels of Zn (7.4 mg/kg, 20.3 mg/kg, 32.1 mg/kg,51.0 mg/kg, 84.4 mg/kg, 169.7 mg/kg, and 332.4 mg/kg diet, supplied as ZnSO4·7H2O. Casein and gelatin were used asdietary protein sources). Each diet was assigned to three replicate groups of 40 fish [initial body weight, (3.6±0.1) g]cultured in 500-L aquaria (r=0.9 m, h=0.75 m). The results showed that the rate of weight gain increased linearly withthe increase in dietary Zn level, then remained nearly unchanged in the high Zn treatment groups (≥32.1 mg/kg). Specificgrowth rate and fish Zn content showed a similar tendency with rate of weight gain. Whole body moisture contentof blunt snout bream decreased significantly in the supplemented groups compared to that in the un-supplementedgroup (P<0.05), whereas whole body crude protein content increased significantly in the supplemented groups comparedto that in the un-supplemented group (P<0.05). No significant difference was observed in the food conversion rateamong the treatments (P>0.05). The serum chemistry analysis showed that dietary Zn had significant effects on contentsof total protein, urea nitrogen, high density lipoprotein cholesterol, total cholesterol, and triglycerides (P<0.05), but noeffect on albumin content or alkaline phosphatase activity (P>0.05). Hepatic malondialdehyde content decreased significantly(P<0.05), whereas superoxide dismutase and catalase remained unchanged with increases in the dietary Znsupplement rate (P>0.05). A broken-line regression analysis showed that the optimum dietary Zn requirement of bluntsnout bream was 32.6 mg/kg for maximum growth and 47.6 mg/kg for maximum fish Zn concentration. These resultsincrease our knowledge of the zinc requirement in blunt snout bream to enhance the feed quality and discover the versatilefunctions of Zn in blunt snout bream.