Prebiotic, probiotic and synbiotic supplementation in diets for juvenile tambaquis at two stocking densities

The objective of this work was to evaluate the effect of prebiotic (mannan oligosaccharides), probiotic (Bacillus subtilis), and synbiotic diet supplementations on juvenile tambaquis (Colossoma macropomum), at two stocking densities, for growth, food utilization, survival, and economic parameters. A total of 192 juveniles (2.4 +/- 0.2 g) was distributed in 32 aquaria (20 L), in a completely randomized design, in a 2x4 factorial arrangement, with four replicates, during eight weeks. Tests were performed for 0.35 and 1.05 kg m(-3) stocking density. The supplementation was constituted of: 2 g kg(-1) prebiotic; 2 g kg(-1) probiotic; 2 g kg(-1) prebiotic + 2 g kg(-1) probiotic; and a control. Stocking density had no effect on fish survival, although it decreased economic and growth parameters. Probiotic and synbiotic supplementation increased growth, and improved feed utilization and economic parameters. The control diet showed the lowest economic efficiency index, while the highest index was obtained by diets supplemented with synbiotic. Growth, food utilization, and economic parameters increased with the probiotic and synbiotic supplementation in diets for juvenile tambaquis, although there is no synergistic effect between the evaluated prebiotic and probiotic supplementations.