Beyond Probiotics: Postbiotics for Healthy Aquaculture.

With a growing global population and strict restrictions on traditional antibiotics, sustainable fish health management is crucial for aquaculture. While live probiotics are popular alternatives, their real-world effectiveness remains highly controversial. Variable effectiveness results from complex interactions with different fish species, differences in fish gastrointestinal anatomy, and variations in environmental parameters such as salinity, pH, and temperature. Furthermore, live probiotics pose risks of ecological disturbance and horizontal gene transfer of antimicrobial resistance. This critical review assesses these limitations and proposes postbiotics, preparations of inanimate microorganisms and their metabolites, as a more stable, controlled, and biosafe formulation. Postbiotics offer significant advantages during industrial aquafeed production and storage. However, their practical implementation is currently hindered by vague terminology and legislative gaps. To overcome these obstacles, this review introduces an innovative modular analytical model utilizing specific chemical biomarkers (such as short-chain fatty acids, bacteriocins, and lipoteichoic acids). Implementing these matrix-matched, multi-module quality control panels to verify molecular safety, identity, and efficacy is critical to standardizing next-generation "precision postbiotics" for sustainable aquaculture development.