Effect of Bacillus Licheniformis Probiotic on the Culture of Hybrid Grouper (♀ Epinephelus Fuscoguttatus × ♂ Epinephelus Polyphekadion)

This study investigated the effect of Bacillus licheniformis VLPPro (R) SB538 supplementation on hybrid grouper's culture water quality, growth performance, and intestinal health. A total of 240 juvenile hybrid grouper were randomly distributed into four experimental groups (n = 20, 718.15 +/- 16.12 g): 0 g/m3 (the control group, WT), 0.375 g/m3 (the low concentration group, WL), 0.750 g/m3 (the moderate concentration group, WM), and 1.500 g/m3 (the high concentration group, WH). The experiment was conducted in triplicate tanks for 4 weeks. Water quality parameters, including ammonia, nitrite, nitrate, and phosphate, were monitored regularly. Growth performance parameters such as weight gain, specific growth rate, and feed conversion ratio were recorded. Additionally, the intestinal health of the fish was assessed by examining the histopathological changes and the expression of intestinal permeability-related substances in the gut. The results revealed that Bacillus licheniformis supplementation significantly improved the water quality in the culture tanks, as evidenced by reduced ammonia and nitrite levels. Furthermore, hybrid grouper in the treatment group exhibited significantly enhanced growth performance, including higher weight gain and specific growth rate, along with a reduced feed conversion ratio compared to the control group. Intestinal health was also positively influenced by Bacillus licheniformis, as indicated by histopathological analysis. Moreover, the decreased concentration of D-lactic and the amelioration of hindgut morphology indicated that Bacillus licheniformis possessed the function of improving intestinal health in hybrid grouper. The findings of this study demonstrate the beneficial effects of Bacillus licheniformis supplementation on the culture water quality, growth performance, and intestinal health of hybrid grouper. The improved water quality and enhanced growth performance can contribute to grouper aquaculture's sustainability and economic viability.