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The effects of dietary supplementation of garlic (Allium sativum) extract on the growth and disease resistance of African catfish, Clarias gariepinus was evaluated. Also in-vitro evaluation of susceptibility of fish-borne multidrug resistant (MDR) pathogenic bacteria to aqueous extract of garlic was done. Aqueous garlic extract exhibited inhibitory activity against MDR bacteria and the degree of inhibition increased significantly with increasing concentration of garlic extract. The garlic supplementation at the rate of 10g/ kg feed improved the food conversion ratio, specific growth rate and protein efficiency ratio of C. gariepinus significantly (p<0.05). On the other hand, it increased the disease resistance of C. gariepinus significantly when challenged with Edwardsiella tarda (p>0.05). No significant difference was observed between plasma protein and glucose levels of the control treatment and garlic supplemented treatment during the 56 days of the experiment. Additionally significant differences in plasma protein and glucose levels of control and garlic supplemented treatments in 2 days and/or 15 days post-challenge. The varying levels of plasma glucose and protein suggested that the stress posed by the bacterial infection persisted in fish even after 15 days of challenge. The results demonstrated that bacterial infection can negatively alter blood biochemical profile of C. gariepinus, and dietary supplementation of garlic extract would help improve the resistance of fish to E. tarda infection in culture condition.

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This study was carried out to evaluate the effect of different levels of garlic (Allium sativum) on growth survival and nutritional characteristics of goldfish (Carassius auratus). For this purpose, 180 goldfish with an average initial weight of 1.18± 0.08 g were introduced randomly into 12 aquaria (50×30×40 cm) in 4 groups, with 15 fish in each group. Treatments were fed on a basal diet for one week, followed by experimental diets for eight weeks. Garlic powder was added at levels of 0 (Control), 0.5, 1 and 1.5 mg kg^-1 to commercial diet. At the end of the experiment, growth and survival rates and feed performance were evaluated. There was no significant difference in growth rate and feed efficiency between treatments, although they were better in the 0.5% level. The highest survival rate was achieved in the 0.5% treatment that showed a significant difference compared to the control diet (p<0.05). The best growth performance and feed efficiency were obtained in fish fed the 0.5% garlic powder diet. 

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This study evaluated the influence of dietary garlic (Allium sativum) extract on survival rate and changes in blood and immune parameters of Common carp (Cyprinus carpio), fed with two different concentrations of aqueous garlic extract after exposure to spring viremia of carp virus (SVCV). The experiments have executed in two steps: Firstly, 270 fingerlings of Common carp with an average weight of 15±3.4 g have cultivated in 18 aquaria with 15 liters of water. Fish were fed with 1 and 5 g garlic extract kg^-1 basal diet for 8 weeks. In the second step, 240 fingerlings have been randomly divided into 8 groups (A: negative control; B: virus control; C and D: extract controls and E-H: treatment groups) with 3 replicates in each group include of 10 fish in each replicate, and the fish have been exposed to SVCV for 4 weeks. The mortality rate, blood and immune parameters and virus isolation have been determined at the end of experiments. The results have showed that the survival rate of the Common carp fed with 1 and 5 g garlic extract kg^-1 basal diet (E-H groups) had a significant increase compared to the control groups (p<0.05) and RBC, hemoglobin, hematocrit, MCH, MCHC had Significant increase compared to the virus control group (B) (p<0.05). WBC in groups D, E, F and G in comparison to control group A and B and lymphocyte in groups D, E and F compared to control group B had a Significant increase (p<0.05). Also, the Common carp fed with two concentrations of garlic extract increased lysozyme and IgM in groups C-H compared to group A (p<0.05). Finally, cell culture and RT-PCR have been applied for detection of SVC virus from fish samples. The results have been indicated that addition of garlic extract (Especially 5 g kg^-1) in fish dietary has led to a higher immunity and survival rate of common carp exposed to SVCV.

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This study examined the dietary impacts of essential oils from garlic (Allium sativum), black seed (Nigella sativa), and black caraway (Carum carvi) on the hematological and immunological parameters of rainbow trout (Oncorhynchus mykiss). A total of 200 fish, each with an average initial weight of 225 ± 10 g, were divided into five groups, each consisting of three replicates with 40 fish per group. The fish were fed for eight weeks with a diet supplemented with 0.2% of the herbal essential oils, while a control group received an unsupplemented diet. The hematological indices, including hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), the number of red blood cells (RBCs) and white blood cells (WBCs), and immune responses, including serum lysozyme and complement levels (C3 and C4), were studied. The analysis showed no significant differences in erythrocyte indices or leukocyte profiles between the control group and the groups receiving essential oils (p>0.05). The control group exhibited the highest values for RBC, Hb, MCV, MCH, MCHC, Hct, and WBC, while the highest percentages of lymphocytes and monocytes were found in the black seed and black caraway groups, respectively. On day 28 of the experiment, there were no significant differences in lysozyme activity among the control and treatments (p>0.05), while a significant difference was observed for black caraway essential oil on day 56 (p<0.05). A significant difference between the control group and all treatments was reported for C3 value on day 28 (p<0.05). Comparisons from days 28 to 56 indicated significant changes for the control versus mixed essential oil, garlic essential oil, and black caraway essential oil (p<0.05). C4 and plasma protein values showed no significant differences between the control group and treatments on both days (p>0.05), however, significant differences were noted when comparing values from days 28 and 56 for the control and treatments of mixed essential oil, black seed essential oil, and black caraway essential oil (p<0.05). The results of this study demonstrated that dietary garlic essential oil significantly enhanced immune functions and TNF-α expression levels in rainbow trout compared to black caraway or black seed essential oils (p<0.05). However, all essential oils boosted immune parameters like lysozyme activity and complement levels, but garlic essential oil showed the most promising results.