This study aimed to investigate the effects of Bonzafish mineral chelated supplement on growth performance, haematological parameters, oxidative indicators, mucosal lysozyme activity and intestinal histology in the koi carp fingerling ( Cyprinus carpio ). For this purpose, 264 juvenile fingerling koi fish with average weight (4.22±0.02) were randomly distributed in 12 tanks, each tank including 22 pieces and fed with varying levels of Bonzafish mineral chelated supplement (control, BF25, BF250 and BF500 mg supplement per kg of diet) for 56 days. The results revealed that the BF250 treatment despite improvement in growth indicators; Only in the parameter of body weight gain compared to BF0 treatment showing a significant difference (P 0.05). The haemoglobin level of fish of BF500 treatment was higher than other treatments so that there was a significant difference compared to BF250 treatment (P 0.05). The number of red blood cells and hematocrit percentage in BF500 treatment was higher than other treatments. There is no significant difference observed between treatments (P 0.05). The number of white blood cells in BF500 treatment showed a significant decrease compared to BF25 and BF0 treatments; The highest white blood cell count was related to BF25 treatment (P 0.05). About the results of measuring secondary haematological indices, MCHC and MCH did not show a significant difference between treatments (P 0.05); But MCV decreased significantly in all three experimental treatments compared to BF0 treatment (P 0.05). About oxidative indicators, the amount of glutathione peroxidase did not show a significant difference between treatments (P 0.05); However, there was a significant increase in the activity of superoxide dismutase enzyme in BF250 and BF500 treatments compared to BF0 treatment (P 0.05). Catalase activity also increased with increasing the mineral supplement level in the diet and was significantly different from BF0 treatment (P 0.05). The amount of malondialdehyde in all three treatments containing mineral supplement showed a significant increase compared to BF0 treatment (P 0.05). Mucosal lysozyme enzyme activity in BF25 treatment was the highest and had a significant difference compared to BF0 treatment (P 0.05). The maximum amount of fold height and intestinal diameter was observed in BF250 treatment which had a significant difference with other treatments (P 0.05). Enterocyte height in BF500 treatment showed a significant increase compared to other treatment (P 0.05). There was also a significant increase in the Microvillus height in BF500 treatment compared to BF25 and BF0 treatments. The proportion of fold height to intestinal diameter also showed the highest value in BF250 treatment, but no significant difference was observed (P 0.05). Therefore, according to the results of this study, it can be concluded that the levels of BF250 and BF500 mineral supplement have a positive effect on some physiological parameters of koi fish, which can ultimately improve growth and production efficiency. Keywords: Intestinal histology, Hematology, Immunity indices, Micronutrients, Chelate.