In the modern high intensity aquaculture, probiotics offer an encouraging substitute to chemicals and antibiotics, one such important application of probiotics is their use as growth promoters, in addition to health and water quality management. On the same background, the study was carried to evaluate the effect of dietary incorporation of probiotic - Bacillus subtilis on the growth performance of grass carp (Ctenopharyngodon idella).The probiotic - Bacillus subtilis was mixed with the basal diet (Protein 32%) in three different concentrations (0.5, 1.0 and 1.5 % designated as T1, T2, and T3). The basal feed with no probiotic was used as control (T0). The impact was recorded for a period of 60 days. Feeding was done twice a day at the rate of 5% of their body weight. Growth performance was evaluated through estimation of weight gain, feed Conversion Ratio (FCR), protein Efficiency Ratio (PER), specific growth rate (SGR) and feed efficiency ratio (FER). It was observed that the probiotic Bacillussubtilis fed at 1.5% significantly improved the growth performance of the fish Ctenopharyngodon idella showing the highest growth rate followed by 1% and 0.5% probiotic fed diets. Lowest growth rate was recorded in control group.

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The present investigation entitled “Studies on growth performance of Cyprinus carpio var. Communis fed with Bacillus clausii supplemented diets” was carried out at Faculty of Fisheries, Ganderbal over a period of 60 days from April 1st to June Ist, 2019. The fingerlings were fed with dry diets containing three concentrations of probiotic viz., (T1: 1%, T2: 1.5%, T3: 2%) and control group (T0: containing no probiotic). The growth parameters including per cent weight gain, Specific growth rate (SGR), feed conversion ratio (FCR), feed efficiency ratio (FER) and protein efficiency ratio (PER) were measured at the end of the experiment. The results showed that the probiotic incorporated diets had significant impact on growth than control group (P<0.05). The highest values of treatment T2 with 2 per cent probiotic showed the highest percent weight gain (74.62%), specific growth rate (0.40), feed efficiency ratio (0.90), protein efficiency ratio (1.82) were observed in treatments with 2% concentration of probiotic where as, feed conversion ratio(1.09) was lower in groups received probiotic through diets than control.