This study aimed to evaluate the effect of the photoperiod on the fillet composition of Nile tilapia juveniles. We employed a completely randomized design with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D, 24L:0D) and four replications. We used 160 Nile tilapia juveniles, distributed in 20 tanks containing 20 liters of water, in a recirculation systems, at controlled temperature of 27 ºC and density of eight fish per tank. Fish were fed twice a day with commercial extruded feed containing 40% crude protein. Samples of the fillet at the end of 75 days were collected and stored in a freezer at -80 ºC for subsequent analysis of chemical composition. There was no effect of photoperiod on moisture and ash content of the fillet (P>0.05). The period 18L:6D showed higher amounts of protein in the fillet, as well as lower amounts of fat (P<0.05). Therefore, it can be concluded that the photoperiod can alter Nile tilapia body composition, and the photoperiod 18L:6D contributed to the higher concentration of crude protein and lower fat deposition in Nile tilapia fillets.
composition; nutrient retention; Oreochromis niloticus