Evaluation of Eucalyptus (Eucalyptus globulus) essential oil on growth performance, hemato-immunological parameters and resistance against Aeromonas hydrophila in fcommon carp (Cyprinus carpio)

Today, the uses of medicinal plants as a growth stimulant and immunity improver have found a special place in the aquaculture industry. In this study, the effect of eucalyptus essential oil on hemato-immunological parameters, growth performance and resistance against Aeromonas hydrophila were evaluated. 240 carp (mean weight 53.64 ± 0.060) were divided into four treatments including a control group and three treatment groups that have received 0.15, 0.3 and 0.6 ml/Kg fish of eucalyptus essential oil by feeding for 8 weeks. At the end of the 8 week, 12 fish from different treatments were anesthetized and biometry then from 9 fish  blood samples were taken. At the same time, 30 fish from each treatment were injected with 0.1 ml intraperitoneally of Aeromonas hydrophilia (with access number JF313402) with a final concentration of 1.2 × 107 (CFU / ml) and thire mortality were recorded for two weeks. The results showed that the level of red blood cells and hemoglobin in all treatments were significantly higher than the control, hematocrit was significantly higher than the control in the treatments of 0.3 and 0.6, the number of white blood cells, oxygen free radical, lysozyme, IgM increased significantly with increasing the dose of the essence. The ALT and AST were not differ significantly between the treated and control groups. The results of growth indices showed that the final weight, body weight gain, specific growth rate were significantly  increase in treatment of 0.6 compared to the control group, but the rate of feed conversion ratio was significantly lower than those control..According to the results, the essence of eucalyptus seems to be a safety stimulant and proper growth in carp and it can be used as a suitable oral supplement in common carp breeding.