author(s)
Anjali P Thilakan, PK Pandey, Manju Lekshmi N, SP Shukla and Sreekanth GB

abstract
This study evaluated the effect of biofloc on water quality and growth performance of Etroplus suratensis for 161 days at ICAR-CCARI, Goa. It included two treatments T1 (wheat flour + formulated feed (2% of fish biomass) and T2 (wheat flour) and a control (formulated feed) with triplicate in 312 L capacity indoor cement tanks filled with 25 L of pond water and 275 L of tap water. The tanks were left for 15 days to make it favorable for the growth of microbes to develop the biofloc. The fingerlings of Pearlspot, Etroplus suratensis with an average body weight of 9.2±0.2 g were stocked at a rate of 50 no. /tank and cultured for a period of 161 days. Specific growth rate (SGR) was recorded significantly (P<0.05) higher in T1 (1.06±0.19), followed by T2 (0.79±0.12) and control (0.46±0.09). Lower pH values were recorded in biofloc tanks may be attributed to the higher rate of nitrification and respiration by microbes. Besides, the addition of carbohydrate has significantly reduced the total ammonia nitrogen (TAN), and nitrate-nitrogen in water. The result of this study concluded that the use of wheat flour (carbohydrate source) along with formulated feed has effectively enhanced the biofloc production which contributed effectively in the maintenance of good water quality, resulting higher production of fish.