Fruit residues as diet ingredients for Symphysodon discus: nutrient digestibility

Abstract

The selection of ingredients is an important aspect for diets formulation for fish in captivity. The use of fruit industry by-products can be an alternative for inclusion in diets for ornamental fish, as discus fish case, to improve health and reduction of production costs, further to reducing the environmental impacts of fruits industries residues. The objective the studies was to evaluate the bioavailability of fruit industry by-products in the diet for discus fish by coefficients of digestibility. The digestibility of three by-products: pineapple by-product, mango by-product, and passion fruit by-product were evaluated. Thirty-two discus fish (106 ± 26.6 g) were distributed in 4 tanks for feeding and fecal collection, constituting an experimental design in Latin square (4 diets test- x 4 periods of fecal collection x 4 replicates). The three by-products had digestibility coefficients above 80%, 70%, and 69% for dry matter, protein, and fat, respectively, being possible to use them as a source of these nutrients in diets for the discus fish. However, it was observed that the mango and passion fruit by-product had the lowest energy digestibility coefficient, with bioavailabilities less than 50% of utilization. The co-products of the fruit processing industry tested in this work have nutritional conditions to be used as food for root discs. The use of these co-products as food for ornamental fish can be an alternative use and value.