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Using of natural plants as immunostimulant in fish is more useful than antibacterial drugs that cause adversely side effects for fish, environment and consumers. Therefore, we investigated the effect of black cumin seeds, Nigella sativa, as a herbal medicine plant on some immuno-hematological parameters and specific as well as non-specific defence mechanisms of rainbow trout, Oncorhynchus mykiss. Fish were fed with basal diet incorporated with 1, 2.5 and 5% Nigella sativa for 21 days. At the end of experiment, the hematocrit (Hct), leukocyte levels, glass-adherent NBT positive cell activation, serum protein and total immunoglobulin level were determined in fish blood. No significant differences (P >0.05) were found in hematocrit levels of fish fed the diets containing 1 and 2.5% black cumin seeds, but it was significantly (P <0.05) increased in fish receiving diet containing 5% black cumin seeds compared to the control. Glass-adherent NBT positive cell activation and leukocyte level in black cumin supplemented groups showed no significant differences (P >0.05) when compared to the control group. The serum protein and total immunoglobulin levels were significantly (P <0.05) higher than those of the control group. In conclusion, based on the current findings together with the low cost and the immunostimulative effect of black cumin seed, it is recommended to be used in fish feed to minimize the mortalities caused by some pathogens.

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I s p i r U . , M . E . Yo n a r : Effects of Levamisole on Phagocytic Activity of Rainbow Trout (Oncorhynchus mykiss W.). Acta Vet. Brno 2007, 76: 493-497. In this study, activation of phagocytic cells was examined in rainbow trout (Oncorhynchus mykiss, W.) exposed to 1, 5 and 10 µg·ml -1 concentrations of levamisole solution. For this purpose, blood samples were taken from fish on days 1, 7 and 14 of exposure. Potential killing activity was determined by measuring oxidative radical production and phagocytic activity of neutrophils and superoxide anion production of phagocytic cells against Y. ruckeri. The activity of phagocytic cells in fish exposed to each of three concentrations was found higher than that in controls and the differences were statistically significant (p < 0.05, p < 0.01). Although no activation in oxidative radical production, phagocytes and bactericidal killing activity in fish exposed to 5 and 10 µg·ml -1 concentrations of levamisole solution was determined on day 7, it was observed that all indicators increased on day 14 of exposure. The present results suggest that the application of levamisole in fish farms could increase non-specific immunity and resistance to infection of fish and offer economics benefits.

Formalin bath treatments are widely used to control of parasitic infections in aquaculture. However, effects of formaldehyde on the lipid peroxidation and antioxidant system were not still need elucidation. Fish were exposed to formalin at doses of 50, 100 and 200 ppm for 1 h. Fish were then left to depurate for 24 h in formalin-free water. At the end of the test, whole bodies were isolated and homogenized to measured malondialdehyde (MDA) and reduced glutathione  (GSH) levels and catalase (CAT) and glutathione peroxidase (GPx ) activities. Results obtained showed that formalin significantly (p < 0.05) increased the MDA level. There was statistically significant decrease in the CAT activity of the experimental groups when compared to the control group. After recovery period, the CAT activity was still found to be lower than the control level. The GPx  activity and GSH level decreased by formalin exposures and did not return to the control values during recovery periods. From the findings of our study, it can be interpreted that acute formalin inhalation may cause oxidative stress and thus, some secondary toxic effects in whole body.

In this study, effects of Yersinia ruckeri antigens on the immune mechanisms of rainbow trout (Oncorhynchus mykiss) were examined. The weight of the 120 fish used in this study was 20-30 g. After injecting 1 mg of formalin-inactivated whole cells (FKC) and O-antigen (Ag-O) intraperitoneally, blood was taken from the caudal vein of anaesthetized fish and metabolic activity of leukocytes (Nitroblue tetrazolium (NBT) activities), phagocytic activity (PA), phagocytic index (PI), serum protein and serum total immunoglobulin (TIg) levels were determined on day 30 after the first immunization. The same procedure was conducted in the control group. In all the experimental groups, considerable increases in the immune indicators were found and significant differences detected between the control and experimental groups (p < 0.05). Metabolic activity of leukocytes decreased significantly (p < 0.05) during the following treatment with antigens compared to the control fish group.

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