EFFECTS OF PHOTOPERIODS ON THE GROWTH PERFORMANCE, FEED INTAKE AND FEED EFFICIENCY OF GILTHEAD SEA BREAM (Sparus aurata) JUVENILES

     In this study, gilthead sea bream (Sparus aurata) juveniles weighting 16.3 ± 0.3 g were reared at a density of 40 fish per 200-L fiberglass tanks for 42 days. The experimental treatments were four photoperiods (6L:6D, 12L:12D, 16L:8D and 24L:0D) with constant light intensity 1500 lx on the water surface. Growth performance, Feed intake, feed conversion efficiency (FCE) and survival rate were investigated. The fish were fed twice daily using a commercial diet containing 46% crude protein at a rate of 2.5 - 3% of body weight/day. The growth measurements were recorded at 15-day intervals during the experimental period. Significantly higher weight gain and specific growth rates were observed in fish exposed to a 24L:0D photoperiod followed by 16L:8D, 6L:6D and 12L:12D photoperiods (P < 0.05), respectively. Feed intake was significantly higher in fish exposed to 24L:0D followed by 16L:6D, 6L:8D and 12L:12D photoperiods (P < 0.05), respectively. The FCE was significantly higher for fish exposed to 24L:0D and 16L:8D than those exposed to 6L:6D and 12L:12D. The carcass contents of all treatments were unaffected (P > 0.05) by varying the photoperiod. These results demonstrated that growth performance, feed utilization and survival rate of gilthead sea bream (Sparus aurata) juveniles weighting 16.3 ±0.3 g can be stimulated significantly by using either a long (16L:8D) or continuous (24L:0D) photoperiod which could be carried out for rearing marine fish juveniles.