Influence of Probiotics on Water Quality and Fish Yield in Fish Ponds

Increased production of fish through intense culture practices often leads to not only stress and disease problems but also alteration in water quality. The organic wastes and bad water quality influence the growth of pathogenic microorganisms. Bioremediation using pond probiotics is considered a promising way to circumvent these problems. For this study, three earthen fish ponds stocked with Pangasius sutchi, Catla catla and Labeo rohita were selected and studied for a culture period. Two ponds were treated with probiotics having Nitrosomonas and Nitrobacter species and one pond was used as control. In these ponds, physico-chemical parameters of water, bacterial loads of total heterotrophic bacteria (THB), beneficial bacteria (Nitrosomonas and Nitrobacter species) and pathogenic bacteria (Pseudomonas), zooplankton and fish yields were studied. The results indicate that the concentrations of ammonia, nitrite and orthophosphates were higher in control ponds than in the treated ponds. In treated ponds, zooplankton, THB and beneficial bacterial loads were observed to be increased whereas pathogenic Pseudomonas loads decreased. Fish yields were relatively higher in probiotic treated ponds (37.35 and 37.00 t/ha/year) than in control pond (32.47t/ha/year). The factors responsible for the improved water quality and high fish yields under the influence of probiotics are analyzed and discussed.