Effectiveness of Bacillus subtilis on growth and survival of common carp larva in non-earthen ponds

Abstract

Introduction: A feeding experiment was conducted to investigate the effect of Bacillus subtilis bacterium and its suitable level on survival and growth rate of larva Cyprinus carpio Mirzakoochek fisheries education center.
Materials & Methods: B. subtilis bacterium isolated from Cyprinus carpio intestine was added to commercial carp feed as a probiotic. Five diets were prepared by soaking carp feed in to the B. subtilis suspension to achieve 104, 105, 106 and 107 levels with a non-treated control.
Result: After 28 days, the larva carp fed diet at level 106, showed a higher mean weight gain (1196.43mg). The mean weight gain showed a decreasing trend as the B. subtilis level decreased and increased from 106 in the diets. There were significant differences (P<0.05) in weight gain, daily growth and feed conversion ratio (FCR) among treated and control groups. There were significant differences (P<0.05) among treatments and control in survival rate but no significant differences (P>0.05) in water quality and biochemical composition among treated and control groups.
Conclusion: It was concluded that the tested strain may be a promising probiotics for larva C. carpio at a level of 106 B. subtillis in to the carp feed.