RAS BASED CULTURE SYSTEM FOR CONTINUOUS PRODUCTION OF ROTIFERS Branchionus calyciflorus IN MASS
The present study was undertaken to find out the preferred food type, minimum algal cell requirement and effective harvest rate for mass production of freshwater rotifer, Branchionus calyciflorus in re-circulatory aquaculture system (RAS) throughout the year. In the first experiment, different food types, viz. Chlorella vulgaris, Spirulina major, Scenedismus obliquus and Baker's yeast, were produced (4000 L) and extensively fed to rotifers with control (5000 L). The highest rotifer count was observed with C. vulgaris food type (365.33±2.18 indi. mL-1) followed by Baker's yeast (245.33±5.36 indi. mL-1) on 8th day and then started declining gradually to 30th day with the count of 229.74±6.32 indi. mL-1 and 144.23±8.41 indi. mL-1 respectively because of lower water quality. In second experiment was conducted to standardize effective harvest rate to maintain rotifer production at its stationary phase. Rotifers were harvested daily at 10%, 30%, 50% and 70% of the total volume (5000 L). The results suggested that daily harvest at 30% has maintained rotifer culture at its stationary phase (381±19.45 indi. mL-1). After standardization of effective harvest rate, we have designed, built and operated mass scale live food production unit with re-circulatory aquaculture system (RAS). The system opens a new perspective of continuous production by treating harvested water using series of filters. The production was done for 17 months and seasonal data showed the highest production was recorded during summer (404.43±24.33 indi. mL-1) followed by monsoon (349.57±25.44 indi. mL-1). The results proved that rotifer can be produced at commercial scale by adopting advanced RAS based technology with minimum water waste.
