Oreochromis niloticus aquaculture with biofloc technology, photoautotrophic conditions and Chlorella microalgae

In this manuscript (Part I), the zootechnical performance of tilapia (Oreochromis niloticus) culture during the nursery and grow-out phases using biofloc technology (BFT) with three photoautotrophic pathway treatments (Chlorella spp., M; Chlorella sorokiniana 2,805, CS; and Chlorella sorokiniana 2,714, CV) was evaluated using high protein feed (40.6%) at a C:N ratio of 7.69:1. Two additional treatments were included as controls: a chemoautotrophic (Q) treatment with a C:N ratio of 7.69:1 and a heterotrophic (H) treatment with a C:N ratio of 13:1. Differences in growth and weight gain were observed among the photoautotrophic treatments and Q and H treatments (p <.05). An increase in nitrates in all photoautotrophic treatments suggests that a chemoautotrophic pathway naturally occurred. For O. niloticus carcasses, the protein (>50.9%) and crude lipid (>23.1%) levels were not significantly different among treatments (p >.05). For the Q treatment, the highest crude protein (42.6%) and crude lipid (1.1%) levels in biofloc were observed during the nursery phase (p <.05). Correlation analyses between the amino acid composition in O. niloticus and that of the feed highlighted deficiencies with regard to methionine, lysine and threonine content despite the high r² value obtained (.9078). In addition, deficiencies in arginine, lysine and taurine were observed in the biofloc (r² =.7265). In Part II, the physicochemical characterization of nutrient residuals and O. niloticus BFT aquaculture integration with hydroponic horticulture in non-recirculated systems is described.