Turmeric Powder, Curcuma longa L., in Common Carp, Cyprinus carpio L., Diets: Growth Performance, Innate Immunity, and Challenge against Pathogenic Aeromonas hydrophila Infection

Microbial diseases cause economic loss in aquaculture on a global scale, and the use of commercial antibiotics for disease treatment produces undesirable side effects. As many medicinal herbs have evolved a potent defense against pathogenic bacteria, there is a growing interest in these herbs as sources for natural antibacterial agents. In this context, this study was undertaken to evaluate the effect of turmeric powder (TP), Curcuma longa, on the performance and innate immunity of common carp, Cyprinus carpio L., and its challenge against Aeromonas hydrophila infection. Fish (1.4 +/- 0.06 g) were fed 0.0 (control), 1.0, 2.0, or 5.0 g TP/kg diet up to satiation twice daily for 10 wk. After the feeding trial, fish of each treatment were intraperitoneally injected by pathogenic A. hydrophila, and they were kept under observation for 10 d during which the daily mortality was recorded. The growth-promoting effect of TP was monitored and observed where fish growth and innate immunity increased significantly as dietary TP levels increased. According to the regression curve, the most suitable TP level for optimal fish growth and health was found to be 2.0 g/kg. On the other hand, TP inclusion in the fish diet did not significantly affect fish body contents. The obtained results indicate that TP supplementation is a promising immunostimulant, which could improve fish performance and innate immunity and prevent common carp aermoniosis at a level of 2.0 g/kg diet.