This study evaluated the effects of a manganese nanocomposite deposited on a carbon carrier (Mn-C) on growth performance, hematological parameters, and the elemental status of carp muscle tissue in order to assess its safety and potential application as a feed additive in aquaculture. The study was conducted on yearling common carp. Three groups were formed using the pair-analog method: one control group and two experimental groups, each containing ten individuals. The experiment lasted 63 days. From day 8 onward, fish in experimental groups I and II received diets supplemented with Mn-C at doses of 0.2 and 0.4 ppm, respectively. An increase in live body weight by 10.9% relative to the control was observed in the group receiving the lowest Mn-C dose (p ≤ 0.001). Several hematological parameters decreased relative to the control, including leukocyte counts (by 39.9% in group I and 36.5% in group II, p ≤ 0.001) and erythrocyte counts (by 62.7% in group I and 47.8% in group II, p ≤ 0.001). At the 0.2 ppm dose, serum glucose, albumin, and total protein levels increased by 73.4, 49.5, and 31.9%, respectively, compared with the control. Changes in muscle elemental composition were also observed: calcium concentrations decreased, whereas sodium and phosphorus levels increased at 0.2 ppm. In both experimental groups, concentrations of essential, conditionally essential, and toxic elements increased but remained within permissible limits. Overall, the Mn-C nanocomposite at the tested doses was found to be safe for common carp.
Mingazova et al. (Mon,) studied this question.