The Effects of Oxytetracycline Antibiotic on the Blood Parameters of Rainbow Trout (Oncorhynchus mykiss) Affected with Aeromonas hydrophila and Efficacy of Butylated Hydroxytoluene on the Improvement of Antibiotic Side Effects

Considering the widespread use of antibiotics in aquaculture and the lack of farmer’s attention to the harmful effects of the antibacterial drugs administration, study of the antibiotic effects on the biological indicators of aquatic animals is necessary. In this study, in order to probe of oxytetracycline effects on blood parameters (red blood cells, white blood cells, hematocrit and hemoglobin) in rainbow trout (Oncorhynchus mykiss) affected by Aeromonas hydrophila, the effects of antioxidant butylated hydroxytoluene (BHT) on the side effects of antibiotic treatments was investigated. By examining the results of this research, which was carried out on 120 rainbow trout fish with an average weight of 175.92±30 g in four treatments (Control, treated with oxytetracycline, treated with oxytetracycline and BHT 0/5% and 0.8% daily diet) and three repetitions, in period of 61 days, BHT antioxidants showed effective roles in improving side effects of oxytetracycline on hematological parameters. On the other hand, due to the lack of significant differences between 0.5 and 0.8 % doses (daily diet) of BHT on blood parameters, it seems the dose of 0.5% is more economic in rainbow trout aquaculture.