Enhancing the Growth Performance of Whiteleg Shrimp, <i>Litopenaeus vannamei</i>, by Salt-Tolerant <i>Bacillus</i> sp.

Probiotics are vital in aquaculture for maintaining water quality, boosting aquatic species' health, and enhancing growth rates. This study investigated the effects of probiotics, namely salt-tolerant Bacillus velezensis MT50 and Bacillus amyloliquefaciens MT51, on the water quality and performance of whiteleg shrimp (Litopenaeus vannamei PL) cultured in tanks. The experimental design included two bacterial treatments and one control treatment (without Bacillus), with each treatment replicated three times. The results indicated that temperature, pH, and total alkalinity varied within the ranges of 27.8 to 28.9°C, 7.81 to 7.94, and 98.5 to 114.7 mg CaCO3 L-1, respectively, and all were maintained at appropriate levels. Additionally, other parameters such as dissolved oxygen (DO), chemical oxygen demand (COD), total suspended solids (TSS), and total ammonia nitrogen (TAN) exhibited less fluctuation in the treatments supplemented with Bacillus sp. compared to the control. Furthermore, the densities of pathogenic agents (e.g., Vibrio) in tanks with the addition of MT50 and MT51 bacteria (102 and 101 CFU mL-1, respectively) were significantly lower than in the control tanks (104 CFU mL-1). The survival rates of shrimp treated with MT50 (70.0 ± 5.3%) and MT51 (86.7 ± 3.1%) were significantly higher (P <0.05) compared to the control group (65.3 ± 3.1%). These findings suggest the potential application of B. velezensis MT50 and B. amyloliquefaciens MT51 as probiotics for sustainable aquaculture practices.