Research highlights: 1. Whiteleg shrimp Penaeus vannamei were bath challenged with Vibrio parahaemolyticus and shrimp had significantly greater survival in biofloc than clear seawater during 96 h post-challenge. 2. Shrimp stocking density (1 to 5 shrimp per 400 mL) did not influence survival of shrimp bath challenged with V. parahaemolyticus in either biofloc or clear seawater conditions. 3. Survival of shrimp bath challenged with V. parahaemolyticus was significantly greater in Nile tilapia-conditioned water prepared at 5 ppt and 10 ppt compared to at 15 ppt and in clear seawater at 5, 10 and 15 ppt. 4. Biofloc and Nile tilapia-conditioned water may protect against acute hepatopancreas necrosis disease (AHPND), and these are inexpensive potential disease management control strategies that could be adopted by the shrimp industry. Statement of relevance: Managed biofloc and Nile tilapia-conditioned water culture conditions can reduce whiteleg shrimp losses due to Vibrio parahaemolyticus (134 characters with spaces)