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Abstract
The current experiment investigated the effect of restricted feeding and partial water renewal in biofloc tank culture on growth and feed performance of Nile tilapia. The design of the experiment included four biofloc treatments, with two feeding levels (75 and 100 grams diet /m3/day) and two partial water renewal rates (weekly and biweekly). The control treatment was fed to satiation, with water renewal each other day. In spite of the differences in growth rates, the higher protein efficiency ratios (2.14- 2.59) and the better food conversion ratios (1.21 {u2013} 1.76 :1 ) observed in the biofloc treatments indicated that it is possible to use restricted feeding when fish are raised in biofloc tanks. The biofloc treatments were more efficient in terms of feed conversion ratios and survival. rate Consequently, the current results suggest that in the presence of biofloc, it is possible to restrict (reduce) feeding rates from satiation to restricted feeding without affecting harvest volume or survival rate. The modified biofloc systems could contribute to the nutrition and physiological health of Nile tilapia.. The results indicated that the rested biofloc treatments were more efficient in terms of FCR and PER values due to feed restriction to 75 to 100 g diet /m3/day. The control treatment which was fed to satiation at 125 g diet/m3/day produced better final body weight and daily weight gain with less feed efficiency, reduced survival rates and higher pumping costs.