Ameliorative and protective effects of prebiotic, microbial levan in common carp, (Cyprinus carpio) fry under experimental exposure to fipronil

This study investigated the immuno-toxicological effect of the insecticide fipronil at sublethal concentration (10% of LC50) and the potential ameliorative effects of dietary microbial levan in Cyprinus carpio fry. Fish were randomly distributed into five treatments in triplicate for 60 days. Five different treatment groups were: levan control L0F0 (basal feed + 0% levan without exposure to fipronil), pesticide control L0F (basal feed + 0% levan with exposure to fipronil), other three dietary supplemented groups exposed to fipronil with different inclusion levels of levan at 0.25% (L0.25F), 0.50% (L0.50F) and 0.75% (L0.75F), respectively. The results revealed that feeding common carp with 0.75% dietary levan significantly reduced (P 0.05) glutathione-S-transferase and glutathione peroxidase levels in various tissues. Lipid peroxidation and heat shock protein level was significantly (P 0.05) reduced with supplementation of levan at 0.75% compared to other groups. Higher glycogen content was observed in high levan fed groups. Although fipronil exposure had no signficiant effect on lipid profile levels, dietary levan supplementation decreased lipid profile level in the fish exposed to fipronil stress. Total immunoglobulin and myeloperoxidase content of common carp showed an increasing trend with the concomitant increase in the level of levan administration in the diet. Overall, results revlealed that microbial levan at 0.75% in the fipronil induced C. carpio fry mitigated the stress due to its potent nutraceutical properties, thus presenting a promising immuno additive for aquaculture.