Effects of butaphosphan and cyanocobalamin mixture on immunity and stress in olive flounder, Paralichthys olivaceus

Background The study evaluated the effects of a butaphosphan and cyanocobalamin mixture on the immune system and stress in olive flounders, Paralichthys olivaceus . Methods The mixture was intramuscularly injected into olive flounders at the current recommended dose. Furthermore, to determine the toxicity of overdose, a histological examination was performed after injection of 1-, 2-, and 4-fold higher than the recommended dose. Results Immunity parameters were altered during the first 2 weeks after a single intramuscular injection of the mixture in olive flounders (average weight 20.5 ± 1.1 g). The levels of all tested items, except glutathione and anti-protease, were higher in the treated group than in the control group in the first week; the levels of all tested items were even higher in the second week in the treated group than in the control group. The level of nitro-blue tetrazolium, myeloperoxidase, and superoxide dismutase between the two groups differed significantly. Changes in the stress response to different seawater temperatures (increase or decrease in seawater temperature by 3–5 °C using 50 L heated or cooled seawater tanks) were studied by determining the changes in cortisol and glucose levels on days 1 and 7. Both cortisol and glucose levels were significantly lower in the treated group than in the control group. Histological analysis did not reveal any abnormalities after intramuscular injection of the mixture at doses that were 1-, 2-, and 4-fold higher than the recommended dose. Conclusions Intramuscular injection of a butaphosphan and cyanocobalamin mixture is safe and effective in reducing stress and improving immunity in olive flounders.