Partial feed restriction and refeeding in rearing Colossoma macropomum juveniles in a recirculating aquaculture system

This study evaluated the effects of partial feed restriction at 1% and 0.5% of live weight (LW) on tambaqui (Colossoma macropomum) juveniles, focusing on growth, carcass composition, health, and tissue morphology. A total of 576 fish (initial weight: 168.7 ± 9.40 g) were distributed across 18 tanks (n = 6 per treatment) and fed a commercial extruded diet with 32% crude protein. Fish were assigned to three groups: PR1 (1% LW), PR0.5 (0.5% LW), and CG (control), in a recirculating aquaculture system. After 28 days of restriction, all groups were re-fed at 3% LW for 56 days and 2.5% LW for 28 days, totaling 112 days. Biometric, organ, and blood analyses were performed on days 0, 28, and 112. Statistical analysis used one-way ANOVA and Tukey’s test (p < 0.05).On day 28, PR1 and PR0.5 showed lower body weight, condition factor, cholesterol, triglycerides, and reduced hepatosomatic and visceral fat indices vs. CG (p < 0.05), without hematological or histological impairment. By day 56, weight gain and feed efficiency improved in both restricted groups. On day 84, PR1 matched CG, while PR0.5 remained lower. At the end (day 112), no significant differences were observed among treatments.. In conclusion, restricting feed up to 0.5% LW for 28 days, followed by refeeding, supports compensatory growth without compromising health, carcass traits, or muscle morphology, representing a feasible and sustainable feeding strategy for tambaqui farming.