Effect of probiotic (Bacillus spp.) addition during larvae and postlarvae culture of the white shrimp Litopenaeus vannamei

This study evaluated different application methods of a Bacillus probiotic (containing Bacillus subtilis, B. licheniformis, and B. pumilus) during the larval and postlarval culture of white shrimp Litopenaeus vannamei across three separate experiments. In experiment I (Nauplius4-5 to Zoea3), probiotic addition to water (Pw) or microalgae (Pm) significantly improved larval survival (80.6% and 80.5%) and wet weight (0.23 mg) compared to controls (67.5% survival, 0.16 mg wet weight). In experiment II (Mysis1 to Mysis3), all probiotic treatments achieved significantly higher survival (83.4–85.6%) than the control (62.9%), with water addition yielding the highest wet weight (1.02 mg vs. 0.48 mg in control) and significantly lowering presumptive Vibrio counts in larvae. In experiment III (PL1 to PL10), zootechnical performance did not differ significantly, but presumptive Vibrio counts were significantly reduced both in culture water (2.04–2.51 × 10^4 vs. 4.12 × 10^4 CFU/mL) and postlarvae tissue (71.3–88.6 × 10^4 vs. 792.0 × 10^4 CFU/g). Direct addition of Bacillus to culture water represents a simple, cost-effective strategy to enhance larval performance and suppress pathogenic Vibrio loads in shrimp hatcheries.