Abstract: In this study, four groups of carp, each containing 12 fish (Cyprinus carpio L.) were chosen. The first group of fish was fed with Cu(II) added pellet fish food, the second group, was fed with thiazole ligand added pellet fish food and the third group was fed with thiazole Cu(II) complex added pellet fish food. The forth group was kept as a control group and was fed only with pellet fish food. Retinol, α-tocopherol and ascorbic acid levels in fish’s muscle tissues were measured using HPLC. Antioxidant vitamin levels of the fish which fed with Cu(II) thiazole complex, were significantly lower than those fed without Cu(II) thiazole complex (p<0.005). It was found that the decrease in vitamin levels correlated with the Cu(II) thiazole complex concentration.