Two levels of clove oil concentrations (0, 75, and 150 ppm) were prepared in 3 separate aquariums, each include 15 fish goldfish, Carassius auratus (average weight of 65 ± 5 g). Fish were exposed to different concentrations of clove oil and kept in aquariums at 18° C until they reach to stage 4 of anesthesia. Blood samples were taken from caudal vein at 0, 4, and 24 hours after anesthesia. Red blood cell count (RBC), hemoglobin concentration (Hb), hematocrit (PCV), white blood cell count (WBC) and the differential leukocyte count (leukogram) were determined by standard hematology method. Results showed that there were no significant differences between values of Hb, PCV and leukogram in each treatment in compare to the same control group (P> 0.05); however, WBC was significantly lower at 4 hours for 150 ppm clove oil treatment group and then returned to normal level 24 hours post anesthesia (P< 0.05). Moreover, RBC in this group was increased significantly after 24 h post anesthesia (P< 0.05). The induction time was less for 150 than 75 ppm clove oil treatment group (90 and 180 seconds respectively). Our results verified that using clove oil up to 75 ppm dose not have irreversible hematological side effect to the goldfish.
