Effect of the digestible protein-energy relationship on the growth performance of Nile tilapia (Oreochromis niloticus) fed fishmeal-free diets

•Twenty diets fishmeal-free comprising different DP levels (140–340 g/kg DP) and DE levels (10.89–13.40 MJ/kg DE) were tested.•Diets containing 240 g/kg DP and 12.56 MJ/kg DE levels are recommended to maximize growth performance of adults Nile tilapia.•The highest fillet yield was noted for the diet containing 340 g/kg DP. This study aimed to determine the best digestible protein: digestible energy (DP:DE) ratio for adult Nile tilapia (Oreochromis niloticus) fed diets formulated with vegetable ingredients (soybean and corn), and without fishmeal. Four hundred and twenty male Nile tilapia (GIFT strain) (initial mean weight 193 ± 12.6 g) were allocated to 60 plastic tanks (1000 L) connected to a water recirculation system, and there were 7 fish in each tank. The experimental design was a 5 × 4 factorial with three replicates for each diet treatment. The fish were fed one of 20 diets containing a combination of five digestible protein levels (140, 190, 240, 290 and 340 g/kg DP) and four digestible energy levels (10.89, 11.72, 12.56 and 13.40 MJ/kg DE) for 96 days. The fish were given three meals each day (8 AM, 1 PM and 6 PM) and feeding was to apparent satiation. At the end of the experimental period, diets presented an interactive effect (P