Biofloc Technology for Nile Tilapia Fry: Technical and Economic Feasibility, Solids Control, and Stocking Density

This study evaluated the technical and economic feasibility of the biofloc technology (BFT) system during the fry rearing phase of Nile tilapia (Oreochromis niloticus), focusing on suspended solids management, stocking density, and economic performance at a pilot scale. Three trials were conducted. The first assessed the effects of four total suspended solids (TSS) ranges (0-200, 200-400, 400-600, and 600-800 mg·L^-1) on larval performance and water quality. TSS levels between 200 and 600 mg·L^-1 promoted improved water quality and zootechnical performance. The second trial tested five stocking densities (2, 4, 6, 8, and 10 larvae·L^-1), evaluating their impact on water quality, survival, and size uniformity. Higher densities negatively affected survival (R² = 0.84) and final weight (R² = 0.92), while also increasing solids and nitrogenous compounds, thus impairing performance (p < 0.05). The third trial monitored six production cycles at pilot scale, evaluating zootechnical parameters, sex reversal efficiency, and economic indicators. All cycles showed survival rates above 85%, sex reversal close to 100%, and positive net margins (18.5 to 41.9%), demonstrating the viability of BFT for commercial fry operations. The results emphasize the importance of controlling suspended solids and stocking density to maintain water quality and optimize larval performance. Furthermore, the system proved economically viable, with good feed conversion rates and profitability, even without water exchange. These findings support BFT as a sustainable and efficient alternative for tilapia fry production, offering significant water savings and promising economic returns when properly managed.