The present study was designed to monitor the effect of herbs garlic and tulsi. Cirrhinus mrigala (mrigal) fish (0.99-1.04 g) were fed on diets supplemented with dried powder of garlic/tulsi at 3 different inclusion level viz., 10, 20 and 30 g Kg-1 of feed for 60 days while control treatment (CC) was not supplemented with any herb. Growth performance, intestinal enzyme activities, nutritional physiological parameters, non-specific immune response and post challenge survival were surveyed. Significantly (P<0.05) higher growth of fish in terms of live weight gain (g), specific growth rate, Apparent protein digestibility (APD), Gross conversion efficiency (GCE) and Protein efficiency ratio (PER) while lower FCR were observed in diets supplemented with herbs when compared to control. Significantly (P˂0.05) high values of digestive enzyme activities (protease, amylase and cellulase), carcass protein coupled with low excretion of metabolites (ammonia and phosphates) were also obtained from herbal supplemented diets. Erythrocyte and leucocyte count; phagocytic ratio and index as well as NBT value were enhanced in fish fed on the plant extract-supplemented diets. A challenge test with Aeromonas hydrophila showed that the fish fed on the garlic/tulsi supplemented diets registered high survival rate. Garlic supplemented diets resulted in better growth and immunomodulatory response as compared to tulsi supplemented diets with feed G3 containing garlic in the proportion of 30 g kg-1 of diet showing best results among all diets indicating that incorporation of herbs A. sativum (garlic) and O. sanctum (tulsi) in optimum dose can promote growth and improve immunity leading to sustainable aquaculture.
