The effects of different amounts of dietary copper and zinc on growth and bone mineralization in common carp was investigated. Experimental fish weighing 55.49 ±6.09 g, divided into 9 groups each with 12 fish, were fed daily at 3% of their body weight. The diets contained copper as sulfate salt (1 and 3 mg/kg diet) and zinc as chloride salt (7.5 and 15 mg/kg diet) and control group was fed with diet containing no additional copper or zinc. A full factorial combination of above treatments (2×2) was performed. Following eight weeks feeding by above-mentioned treatments, eight fish were randomly taken from each tank and blood samples were taken from the caudal peduncle vein. The serum parameters related to bone metabolism, including total calcium, inorganic phosphorus, magnesium and alkaline phosphatase were measured. In addition, calcium, phosphorus, magnesium and ash contents of bone were determined. The histology of bone tissues was also studied. Based on the results, the added amount of copper and zinc to the diet, had no significant effects on growth performance, but the biochemical serum parameters related to the bone metabolism were affected. In comparison to control group, serum alkaline phosphatase activity was reduced in all treatments. Although no significant differences were found between the serum calcium content of control group with Zn-treated group, significant differences ( P 0.05 ) were observed in combined treatments (Cu+Zn). Serum inorganic phosphorus showed a declining trend in all treatments as compared with control group, except for Zn2 and Zn1+Cu1. Although serum magnesium content was remained steady in most groups receiving Zn and Cu separately, fish receiving both ions showed a reduction compared with control group. The content of calcium, phosphorus and magnesium in bone tissue was affected by diet. Regardless of the statistical significance, the amounts of calcium and phosphorus in bone tissues of fish declined in all treatments as compared to the control group. Copper treatments showed a decrease in magnesium content of bone during the experiment. The ratio of calcium to phosphorus and percentage of ash content in bone tissue of fish were similar in all treatments. Osteocytes abundance in boney tissue of fish in all single and combined treatments was much higher than the control group. Generally, changes in the amounts of copper and zinc in diet result in altering serum biomarkers of bone metabolism in carp. Hence, by changing the amounts of copper and zinc in diet, bone mineralization might be affected. Key words: Growth, Bone mineralization, Copper, Zinc, Cyprinus carpio
