Biofloc Technology Improves Harmful Nitrogen and Pathogens Control and Enhances Production Performance in Intensive <i>Penaeus vannamei</i> Culture Ponds with Reduced Water Exchange

This 90-day trial evaluated the integrated benefits of biofloc technology (BFT) in lined ponds for intensive <i>Penaeus vannamei</i> culture, comparing it with a conventional water-exchange (WE) system. The BFT system maintained favorable water quality with a 68.4% reduction in cumulative water exchange. Concentrations of toxic total ammonia–nitrogen (TAN) and nitrite–nitrogen (NO₂⁻-N) were better controlled, and total suspended solids (TSS) stabilized within a beneficial range (150–200 mg L⁻¹). Microbial analysis indicated that BFT significantly increased total bacterial abundance in both culture water and shrimp hepatopancreas while reducing the total <i>Vibrio</i>-to-bacteria ratio in culture water to below 6%, significantly lower than in the WE system (>18%). Moreover, BFT significantly lowered the loads of specific pathogens, acute hepatopancreatic necrosis disease (AHPND)-causing <i>Vibrio parahaemolyticus</i>, and <i>Enterocytozoon hepatopenaei</i> (EHP) in both culture water and shrimp hepatopancreas. Regarding production performance, BFT significantly enhanced shrimp survival rate (82.4% vs. 71.5%), yield (3460 vs. 2948 kg pond⁻¹), and water productivity (0.85 vs. 0.28 kg m⁻³), while lowering the feed conversion ratio (1.16 vs. 1.33). In conclusion, BFT achieves stable water quality, effective pathogen suppression, and enhanced production efficiency through microbial regulation, offering a viable water-saving, environmentally sound, and disease-resilient strategy for intensive <i>P. vannamei</i> culture.