On the 5th day, biofloc was allowed to settle by closing the aeration and subsequently harvested by passing water in nylon filter bag with 10 μm pore size. The collected floc centrifuged at 2000 rpm and discarded the supernatant water. To remove the traces of ammonia nitrogen level, bioflocs were washed twice with filtered brackish water of same salinity. Flocs were dried under shade on a polythene sheet followed by drying in a hot air oven at 45 °C. The dried flocs ground in to fine powder (less than 200 μm) and kept in airtight containers in refrigerator until experimental diets were made.