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The Brazilian sardine is the most important fishery resource in Brazil. Their production has declined along the last 30 years due the overfishing, climatic and oceanographic phenomena. This study was carried out to determine the optimal feeding frequency for juvenile Brazilian sardine based on growth, feed efficiency, feed intake and body composition. Six feeding frequencies of one, two, three, four, five and six times a day were evaluated in triplicate tanks for 50 days. Fish with initial mean weight of 3.29 AE 0.56 g were fed daily to apparent satiation. The results showed that fish fed once daily had lower body weight gain, specific growth rate and condition factor (P < 0.05) compared with other treatments. The feed efficiency ratio in fish fed once daily was significantly higher (P < 0.05) than those fed two or more times a day. No significant differences were observed in the coefficient of variation in body weight (P > 0.05) among the treatments. Feed intake was directly proportional to the feeding frequency. Fish fed once daily showed lower hepatosomatic and mesenteric fat indices (P < 0.05) than the other treatments. Neither protein nor ash content of fish were significantly (P > 0.05) affected by feeding frequency. However, the lipid content increased with feeding frequency. The results suggest that the optimal feeding frequency for juvenile Brazilian sardine is at least twice daily.

A 6-week growth trial was conducted to evaluate the effects of feeding rate on growth performance, body composition, plasma metabolites and enzyme activities, and to determine the optimal feeding rate for juvenile Brazilian sardine. Fish were fed at six feeding rates, 2, 4, 6, 8, 10% BWday −1 (body weight per day) and until satiation (10.3% BWday −1 ). The survival of fish fed at 2%-6%BWday −1 was significantly higher (p < .05) than the survival of fish fed at the other feeding rates. The final body weight and specific growth rate significantly increased (p < .05) with increasing feeding rates while feed utilization decreased. Total proteins, cholesterol and triglycerides concentrations increased significantly with increasing feeding rates; however, there was no significant effect on glucose levels. Body protein and ash contents were not affected by the feeding rates. Whole-body lipid content increased significantly as the feeding rate increased, while moisture content had an opposite trend. Proteases and amylase activities significantly decreased with increasing feeding rates, while lipase activity was not influenced by the feeding rate. Our results suggest that low feeding rates stimulate mobilization of metabolites to supply energy for the maintenance of overall metabolism and digestive enzyme activities increase to enhance feed utilization. The optimum feeding rate of juvenile Brazilian sardine based on PRR as determined by the second-order polynomial regression was 5.45% BWday −1 . K E Y W O R D Sbody composition, brazilian sardine, digestive enzymes, feeding strategy, fish nutrition, plasma metabolites