Optimization of Feeding Rate for Hatchery‐Produced Juvenile Gilthead Sea Bream Sparus aurata

.— A 61-d growth trial (five 11-d feeding periods) was conducted to determine the effects of feeding rate on growth, feed utilization, morphology, and body composition of the gilthead sea bream Sparus aurata. Gilthead sea bream juveniles with an average initial body weight of 3 g were fed a commercial diet (51% crude protein, 11% crude fat) at rates of 0.5, 1.0, 1.5, 2.0, 2.5, or 3.0% of their body weight (BW) per day in two equal meals. Water temperature was approximately 21.4 C throughout the experiment. Each ration was administered to triplicate groups of 60 fish, with ration readjusted every 11 d. Growth rate was measured as specific growth rate (SGR). Survival rate and coefficient of variation did not differ significantly among the groups fed different rates. Body weight, condition factor, and hepatosomatic and viscerosomat-ic indices displayed significant increases with increasing feeding rate from 0.5 to 3.0% BW/d. Fish fed 0.5% BW/d had significantly higher moisture and ash and lower protein contents than those fed at higher rates. Moisture and protein contents were not significantly different for fish fed at the highest feeding rates (2.0, 2.5, and 3.0% BW/d). Lipid contents increased significantly with increasing feeding rate from 0.5 to 3.0% BW/d. The SGR showed a curvilinear significant increase when the feeding rate was increased from 0.5 to 3.0% BW/d. Feed efficiency (FE) increased significantly to a maximum value with increasing feeding rate from 0.5 to 2.0% BW/d and decreased significantly with increasing feeding rate from 2.5 to 3.0% BW/d. Based on the data obtained, feeding rates of 2.3% and 0.6% BW/d are recommended as optimum and maintenance rations, respectively.