Biofloc technology (BFT) is an environmentally sustainable aquafeed and an innovative ecological farming technique used to reduce nitrogen concentrations and pollutants from aquaculture. This study investigates the use of biofloc nitrogen by tilapia (Oreochromis niloticus), integrated with freshwater mussel (Coelatura cridlandi) in a biofloc system. Biofloc was prepared using brown sugar as an additional carbon source (33% carbon) in a concrete fish pond (25m³), maintaining a C/N ratio of 20 and a total suspended solid concentration of 250 mg L⁻¹. The experiment, carried out in 400L tanks, tracked the dynamics with biofloc as the sole feed source for 30 days. Key water quality parameters such as total ammonia nitrogen (TAN), nitrate (NO3--N), nitrite (NO2--N), pH, temperature, dissolved oxygen, and salinity were monitored. The results indicated that the TAN concentrations were significantly lower in the treatment tanks after 15 days (P<0.05). A total of 47 species of microalgae were identified, with the highest number of potential microalgae (Bacillariophyta and Chlorophyta) observed in the treatment groups. The study also showed significantly lower concentrations of Vibrio-like bacteria (VLB) in biofloc treatments compared to the control (P<0.05). The results suggest that the quality of the water improved significantly due to the substantial consumption of biofloc by tilapia in the integrated treatment with both tilapia and mussels. High nitrogen uptake values indicate that tilapia can efficiently use biofloc for growth, providing a promising theoretical foundation for future research on freshwater polyculture models.
Keywords: Bio-floc; tilapia; freshwater mussel (Coelatura cridlandi); integrated system; water characteristics.