In order to does this study, 150 Persian sturgeons having 75g mean weight transferred to 500 liter tanks. After dividing the fishes into two groups (experimental and control), the fingerlings fed by concentrate food that contained different levels of Zataria multiflora essential oil (15, 25, 50, 100 g/kg) for 8 weeks. Finally, sampling carried out on blood and serum of fishes. After preparing the samples based on standard methods, hematology and serology studies, performed. The results showed significant difference in mean of monocytes between experimental and control groups (P0.05), but there is significant difference in mean and standard deviation of albumin. So that, the average in treatments 15 and 25g/kg and control group was more than treatments 50 and 100g/kg of Zataria multiflora essential oil
