BACKGROUND: Obtaining an appropriate anesthetic drug for rapid anesthesia with long term and safe recovery has always been the concern of fisheries science researchers. OBJECTIVES: In this study the anesthetic strength of Lavendula officinalis essence oil on histopathological and blood biochemical factors of Hypophthalmichthys molitrix has been investigated. METHODS: 260 juvenile silver carp were divided into four groups with a mean weight and length of about 23.55±1.5 g and 15.6±1 cm, respectively. Three groups were anesthetized with concentrations of 200, 300 and 400 ppm Lavender essence oil and 4 groups were considered as control group. The time needed to reach different stages of anesthesia was recorded and in two times (0 and 24h after anesthesia), hematology tests were conducted. After removing plasma serum by centrifugation, ALP, AST and ALT amounts were measured, venesection histological (sampling of liver, kidney and gills) and conserved for histology. RESULTS: Lavender essence oil anaesthetizes Hypophthalmichthys molitrix in less than 3 minutes and recovery time was also less than 3 minutes. Moreover, anesthesia with different concentrations of lavander had no effect on hematological profile and no significant changes in the AST, ALT and ALP were observed (p<0.05). Histopathological analysis showed the optimum concentration of 300 ppm with no side effects and indicated that the concentration power of essences can be used without fear of damage. CONCLUSIONS: It is advised that Lavender essence oil be used as a standard medicine to anesthetize and supersede prevalent chemicals to create anesthesia and sedation in fish.