Live Food Microbial Management and Its Role in Conditioning the Larval Rearing Environment

Microbial management in aquaculture hatcheries is critical during early larval development to prevent opportunistic bacterial proliferation and establish beneficial microbiota. This study evaluated disinfection and Bacillus-based microbial management protocols during rotifer and Artemia production, assessing their impact on the rearing environment and gilthead seabream (Sparus aurata) larval performance. Rotifers were treated with Sanolife MIC-F and Sanocare SURE, while Artemia were produced using EG SEP-Art D-FENSE combined with Bacillus enrichment and cold storage sanitation. Treated live food was fed to seabream larvae in duplicate 6,000-L tanks until weaning at 55 days post-hatch (dph). Disinfection protocols resulted in cleaner Artemia with approximately 2-log reductions in total bacterial and Vibrio loads per nauplius, while successfully incorporating ~1.6 × 10³ Bacillus per nauplius. In rearing tank biofilms, Bacillus persisted up to 30 dph when applied via rotifers and up to 56 dph (~10⁵ bacilli per 0.5 cm²) when delivered through both live foods. While larval growth and survival did not differ significantly under standard conditions, microbial management conditioned the rearing environment with beneficial communities, supporting system resilience.