Investigation of Different Levels of Water Oxidation Reduction Potential (ORP) on Physicochemical Parameters of Water, Blood Biochemical Indices and Cortisol Hormone of the Common Carp (Cyprinus carpio)

Water Oxidation Reduction Potential (ORP)is a physicochemical indicator of water that is affected by a combination of oxidation and reduction agents in water and wastewater. In addition to affecting many water quality parameters, this indicator alone indicates a general quality of water and wastewater. With due attention to the importance and effects of this indicator on aquatics biosafety, the present study aims to investigate of different levels of water Oxidation Reduction Potential (ORP) on blood biochemical indices and cortisol hormone of the Common carp (Cyprinus carpio) and water physicochemical parameter includes COD, BOD, TOC, nitrate and phosphate. To do this research, 72 numbers of the common carp with an average weight of 60±5 gr in 4 treatments with ORP levels 200-250 (control), 250-300, 300-350, 350-400 mv in triplicates were performed. The studied fish were moved in 70 liter tanks for 4 weeks research period. During the research, different levels of ORP in different treatments and the ozone generator was set daily and the ORP measurement was done with the digital ORP-meter device. The results showed that at the end of the study that with increasing trend of ORP levels in the treatments, cortisol hormone levels increased significantly in the fish body. Results of blood biochemical indices included white blood cell count (WBC), red blood cell (RBC), mean cellular volume (MCV) and neutrophil with Increased ORP levels were directly increased significantly based on ORP levels. However, between mean levels of hemoglobin (MCH), hematocrit (HCT), hemoglobin (HB), moderate hemoglobin concentration in red blood cells (MCHC) and monocyte there were no significant difference in the treatments. In general, the results of the research showed that the ORP level in the range of 200 to 300 mv not only has not a negative effect on the fish and their mortality, but also improves the conditions for fish species by improving the water quality indices.