Microplastics accumulated in bioflocs can potentially jeopardize fish health and threaten the sustainability of aquaculture. Although biofloc technology (BFT) improves feed efficiency and water quality, the interaction between microplastics and bioflocs and their impact on fish remains an under-researched issue. This study explored the dynamics of microplastics in biofloc systems used for tilapia (Oreochromis niloticus) aquaculture to understand the accumulation of microplastics in bioflocs and fish tissues and their impact on fish health and ecological risks. Four treatments were applied: control without bioflocs and microplastics (A), bioflocs without microplastics (B), bioflocs with polyethylene (PE) microplastics of 80 particles.L-1 concentration (C), and bioflocs with PE of 800 particles.L-1 concentration (D). Microplastics were extracted from fish tissue using the NaCl solution density method and characterized using ATR-FTIR to identify polymer types. Results showed that in the treatments without microplastics (A and B), the accumulation of microplastics in fish tissues was shallow, with 0 particles.g-1 in muscle and an average of 1.667 particles.g-1 in the intestine. However, in treatments with microplastics (C and D), the accumulation increased significantly to 0.25 particles.g-1 in muscle and 9 particles.g-1 in the intestine for treatment D. The polymer types identified included polyethylene (PE), polyamide (PA), and polyethylene terephthalate (PET). The ecological risk index showed that the PLI ranged from 1.386-2.038, while the PHI reached a value of 122.966-212.665, indicating a high hazard level. This study confirmed that bioflocs without microplastics significantly reduced the risk of contamination in fish, while bioflocs with microplastics increased exposure and toxicity. Management of microplastic waste is essential to support aquaculture sustainability and food safety.