Compensatory growth of Piaractus mesopotamicus raised in net cages and subjected to a period of fasting and refeeding

The present study evaluated the effects of feed restriction on production, blood and tissue parameters of Piaractus mesopotamicus raised in net cages. The experiment was divided into two phases. In phase I, which lasted for 30 days, 960 P. mesopotamicus (368.44 ± 155.05 g) were distributed in a completely randomised design in six net cages with two treatments and three replications each, namely: fish subjected to 15 days of feed restriction followed by 15 days of feeding (FR) and fish fed continuously (CF). In phase II, which lasted for 60 days, 600 P. mesopotamicus (780.40 ± 96.07 g) were distributed in six net tanks, with the same treatments as were used in phase I. Growth performance parameters did not differ significantly between treatments (p > 0.05) in both experimental phases. However, feed intake was significantly lower in the FR fish (p < 0.05). In phase I, higher haemoglobin and erythrocyte levels were observed in the FR fish compared to the CF fish (p < 0.05). In phase II, no significant differences (p > 0.05) were observed in blood parameters between treatments. The hepatocyte histomorphometric parameters of pacu demonstrated no significant variation between treatments (p > 0.05) across both phases. The protocol of biweekly cycles of feed restriction followed by refeeding did not harm the growth of P. mesopotamicus raised in net cages and had minimal effects on blood and hepatocyte histomorphometric parameters.

Keywords:
feeding strategy; fish farming; neotropical fish; pacu