Egg disinfection improves larval survival and shapes the microbial community in snubnose pompano (Trachinotus blochii).

Early microbial colonization is crucial for immunity and survival in aquatic animals. This study evaluated the impact of egg disinfection on microbial colonization and larval performance in Trachinotus blochii, a high-value mariculture fish. Optimal egg disinfection protocols were initially identified as 20 ppm iodophor for 10 min, 400 ppm H₂O₂ for 10 min, and 40 ppm glutaraldehyde for 5 min to improve hatchability. Sequential analyses included 16S rRNA amplicon sequencing of larval microbiota at 10-days post hatching (DPH) and assessment of survival and antioxidant status till 25 DPH. Disinfection significantly enhanced hatchability (up to 90.88 ± 2% with 40 ppm glutaraldehyde), larval survival (up to 34.80 ± 1.1% in glutaraldehyde and 31.18 ± 1.5% in H₂O₂), and catalase activity. Notably, egg disinfection reshaped the larval microbiota, enriching microbial diversity measures and beneficial bacterial taxa, such as Hyphomonadaceae, Halieaceae, Nannocystaceae, and Alteromonadaceae. Improved survival correlated with enhanced taxonomic and functional metagenomic diversity, lower Proteobacteria: Bacteroidota ratio and higher combined proportions of Fusobacteriota, Firmicutes, and Bacteroidota relative to Proteobacteria. The findings suggest that egg disinfection acts as a microbiota programming strategy to promote larval health, offering a practical approach to enhance sustainability in T. blochii aquaculture.