Effects of Viscum album and Nigella sativa extracts on survival rate, growth factors and resistance to Aeromonas hydrophila infection in gold fish (Carassius auratus)

BACKGROUND: Recently several types of herbal immune and growth stimulants have been used in aquaculture troughout the world. OBJECTIVES: This study was performed to evaluate the effects of oral administration of Viscum album and Nigella sativa extracts, on survival rate, growth factors and resistance against Aeromonas hydrophila infection in gold fish. METHODS: 270 gold fishes were divided into 2 immune and non-immune groups and each group into 3 treatments; V.album, N.sativa and control (each with 3 repeats). Each treatment groups fed for 7 weeks with food supplemented with 0.5% of V.album, N.sativa or water. At the end of treatment, survival rate, growth factors and resistance to A.hydrophila infection were compared among the groups. RESULTS: Percentage of mortality in different groups were 9.33 to 12% and prescription of either extracts has no significant effect on survival of groups (p>0.05). Food conversion rate and percentage of weight gain were 2.56±0.31 and 131.6±25.05% in V.album treatment and 3.12±0.37 and 73.2±4.53% in control treatment, respectively which showed a significant increase (p<0.05), growth factors didn't show any significant difference between N.sativa and control treatments (p=0.15). Mortality rate after bacterial infection showed a significant decrease in V.album treatment (p<0.05) in a way that mortality in V.album treatments of immune and non-immune groups were 40 and 80% and in control treatment were 63.3 and 100%, respectively. N.sativa had no significant effect on mortality after challenge (p=0.45). CONCLUSIONS: Oral administration of V.album in gold fish has similar effects on immune and growth stimulation as those reported in other warm-blooded animals but N. sativa didn't show such effects.