Effects of feed restriction to enhance the profitable farming of blackhead seabream Acanthopagrus schlegelii schlegelii in sea cages

The feed intake, growth and body composition of juvenile blackhead seabream Acanthopagrus schlegelii schlegelii (Sparidae) (5.6 g fish^?1) were investigated for 16 weeks in sea cages under seven repetitive feeding cycles: every day feeding (control), 6-day feeding and 1-day fasting (F_6.1), 5-day feeding and 1-day fasting (F_5.1), 4-day feeding and 1-day fasting (F_4.1), 3-day feeding and 1-day fasting (F_3.1), 2-day feeding and 1-day fasting (F_2.1), and 1-day feeding and 1-day fasting (F_1.1). The survival of the fish during the experimental period was not different among the feeding cycles. The greatest weight gain of fish was observed in the control, but not significantly different from that of the F_6.1 and F_5.1 groups (p > 0.05). Total feed intake and daily feed intake decreased with the increase of fasting frequency, however, actual feed intake, feed efficiency and protein efficiency ratio increased with the increase of the fasting frequency. Proximate composition of the whole body of fish was not affected by different feeding cycles. These results suggest that juvenile blackhead seabreams subjected to repetitive feeding cycles of 6- or 5-days feeding and 1 day fasting for 16 weeks could achieve compensatory growth, and that such mild feeding deprivation could save significant amounts of feed without causing any profit reduction that might result from a decrease in fish size or quality.