Influence of brief immersion in an aqueous solution of sodium chloride and/or copper sulphate on pikeperch (Sander lucioperca (L.)) blood parameters

Research focusing on the effects of chemotherapeutics on the physiological state of fish determines their application in aquaculture. The aim of the study was to determine the impact of sodium chloride (NaCl) and/or copper sulphate (CuSO₄) on the hematological and biochemical parameters of the blood plasma of pikeperch, Sander lucioperca (body weight – 346.42 ± 44.82 g; body length – 29.8 ± 1.3 cm) during rearing in recirculating aquaculture systems (RAS). Three groups of fish were subjected to treatment with NaCl (5 g/L), CuSO₄ (1.5 mg/L), and NaCl+CuSO₄ (5 g/L + 1.5 mg/L). Blood was drawn 0, 24 and 48 h following immersion. Significant differences were noted immediately following the conclusion of immersion: mean corpuscular volume (MCV; elevated values in the NaCl+CuSO₄ group) and mean corpuscular hemoglobin concentration (MCHC; elevated values in the NaCl group). Immediately following fish exposure in all three experimental groups (0 h), significantly elevated glucose and lactic acid levels were recorded as were lowered levels of chloride ions (Cl^-). After 24 and 48 h, significant differences were observed in Cl^-. In the NaCl group lowered levels of this parameter were sustained after 48 h, while in the other two groups this was sustained for 24 h. It was confirmed that the physiological impact on the pikeperch of the prophylactic bath in sodium chloride and/or copper sulphate was short and that the treatments did not have a significant impact on the health condition of pikeperch.