Pirarucu is one of the main fish species for the development of aquaculture in the Amazon. In this study, the optimal feeding frequency for juvenile pirarucu was assessed based on growth and feed efficiency. Juvenile pirarucu weighing ca. 80 g were fed once, twice, three or four times daily until apparent satiation for 63 days. Fish fed three or four times per day presented higher growth, feed intake, and fat body content than those fed once or twice per day. There was no significant difference for feed conversion ratio, and protein and energy retention rates among treatments, suggesting that increased feeding frequency did not affect feed utilization efficiency. Mean feed intake per meal was higher when fish were fed once per day, possibly causing hyperphagic behavior. Results suggest that feeding three times per day was sufficient to secure adequate feeding and growth of juvenile pirarucu. (AU)