Effects of garlic (Allium sativum) extract on growth performance, survival rate, some hematological and biochemical indices of Gourami (Trichogaster trichopterus)

Nowadays, the healthiness and high quality as well as quantity of aquatic are of great importance and the role of diet components is well recognized (20). Fish needs energy and nutrients in order to achieve desirable level of growth and development and reproduction (11). In recent years application of immune system stimuli has been widely adopted in order to enhance the immune system of fish and non-specific immune responses and protect against disease. So it seems that using stimulator of the immune system is the perfect solution for the control of aquatic animal diseases. Using chemical drugs and antibiotics in aquaculture have consequences, including the risk of pathogens resistant to these drugs, the drugs persistence in the meat and fish as well as environmental pollution. Taking herbs and medicinal plants such as garlic fraught with same effect as antibiotics can be served as an alternative to medications and antibiotics. In this study, 180 gourami fish with average weight 0.10 ± 4.33 were prepared from reproduction and breeding center of ornamental fish in Golestan province. To add the garlic oil to the diets, the standard meal was purchased from commercial fish feed company of Mazandaran province and were ground using a mortar. Then, garlic oil at levels of 0, 0.10, 0.15 and 0.20 g/kg was added to water and mixed. Fish were fed for 8-weeks in three times by 3% body weight per day at hours 8-14-20. Fish diets and their growth rate monitored by conducting bio-survey at the beginning and during the growth for,every 15 days. 10 fish were sampled from each replicate to take serum. After anesthesia using 0.7 ml 2-phenoxyethanol, fish were dried, and about 2 ml of blood was taken by cutting the tail. In hematology laboratory, number of white blood cells, red blood cells, hemoglobin and hematocrit were measured according to standard methods. Glucose levels and serum protein were measured by spectrophotometry using a diagnostic kit (Sigma, America). Data analysis was performed using one-way analysis of variance (ANOVA) in SPSS software. Significant differences (P