Digestibility and performance of tambaqui fed diets containing passion fruit (Passiflora edulis) and tucumã (Astrocaryum vulgare) residues

This study evaluated the effects of including passion fruit (Passiflora edulis) and tucumã (Astrocaryum vulgare) residues in the diets of juvenile tambaqui (Colossoma macropomum) on apparent digestibility and growth performance. Three isoproteic and isocaloric diets were formulated: a control diet (without residues), one with 20% passion fruit residue, and another with 20% tucumã residue. The trial lasted 45 days and followed a completely randomized design with three replicates per treatment. Apparent digestibility coefficients (ADCs) of dry matter, crude protein, ether extract, and energy were assessed, as well as weight gain, feed conversion ratio, specific growth rate, and protein efficiency ratio. The fish fed the control diet achieved superior growth and nutrient digestibility. In contrast, the residue-based diets resulted in reduced performance and lower nutrient retention in the carcass, likely due to the high fiber content and low nutrient availability of the ingredients. These results suggest that the direct inclusion of 20% of these residues may not be suitable for juvenile tambaqui. However, these ingredients may become viable alternatives when used at lower levels or after proper processing, contributing to the sustainability of Amazonian aquaculture without compromising the nutritional adequacy of the diets.