This study was carried out to compare the dietary toxicity of organic zinc (Zn-proteinate, Bioplex Zn®), mineral zinc (ZnSO4), and nanoparticulate zinc (ZnO-NPs) on the basis of some biological responses including growth performance and whole-body proximate composition, and antioxidant enzymes, as well as their accumulative affinity to target organs. These Zn sources with the nominal concentrations of 0, 30, 100, and 500 mg kg−1 diet were added to a basal diet. Juvenile common carp (n = 400; weight of 25.3 ± 2.7 g) were fed with the diets for 56 days. ZnSO4 significantly reduced condition factor (CF) at 500 mg kg−1 diet. The highest activity of superoxide dismutase (SOD) and alkaline phosphatase (ALP) was observed in the plasma of the animals received 500 mg kg−1 diet of all experimental Zn sources. However, this concentration of ZnO-NPs significantly increased the activity of SOD when compared to the respective amount of ZnSO4 and Zn-proteinate. Catalase (CAT) showed a zinc-concentration decreasing activity; the minimum activity was observed in the fish group treated with the diet containing 500 mg kg−1 ZnSO4. Digestive, muscular, and integumentary systems demonstrated the following tissue zinc burden: liver > muscle > bone > posterior intestine ≈ skin > anterior intestine, for ZnO-NPs; liver > muscle ≈ bone ≈ posterior intestine ≈ skin > anterior intestine, for Zn-proteinate; and liver > muscle ≈ bone ≈ skin > posterior intestine ≈ anterior intestine, for ZnSO4. Based on accumulative affinity, taken together, ZnO-NPs displayed the highest affinity to all of the analyzed target organs, and also intestinal Zn accumulation suggested that the gut tissue has the lowest rendering ability against ZnO-NPs in compare to ZnSO4 and Zn-proteinate.
