The present study investigated the effects of thyme and thymol as phytoadditives on hematological and non-specific immune serum biochemical parameters in Oreochromis niloticus. In this trial, ninety (90) O. niloticus with an average body weight of (50 ± 5) were used. Fish were divided into three groups (30 fish/each group) in triplicate and fed for 8
weeks with (group 1) fed basal diet as the control group, while (group 2) and (3) were fed basal diet supplemented with thyme at 10g/kg diet and thymol at 3g/kg body weight, respectively After 8 weeks of feeding groups (2) and (3) showed particular differences in the immunological and hematological parameters as compared to control group, a significant
increase of phagocytic and lysozyme activity were seen in the treated groups. Also, the serum total protein and globulin levels were significantly higher after experimental infection in comparison to the control. The results of the present study indicated that dietary supplementation of 3 g/kg of thymol and thyme in 10g/kg in commercial diets could improve some non-specific immunity and biochemical parameter in O. niloticus and increase survival rate against experimental challenge with Strept .Sp.