Probiotic Bacillus subtilis Improves Hematological, Growth, and Gut Health Performance in the Nile Tilapia (Oreochromis niloticus) Cultured Under Salinity Stress

Et Al., Rahmi

doi:10.21608/ejabf.2025.411322.6355

Probiotic Bacillus subtilis Improves Hematological, Growth, and Gut Health Performance in the Nile Tilapia (Oreochromis niloticus) Cultured Under Salinity Stress

Document Type : Original Article

Author

Rahmi et al.

10.21608/ejabf.2025.411322.6355

Abstract

The Nile tilapia (O. niloticus) cultivated in waters with elevated salinity often face stress that negatively impacts their growth, immune system, and intestinal health. This study investigated the effects of adding the probiotic B. subtilis to the diet at various doses (10³, 10⁵, 10⁷, and 10⁹ CFU/mL) on the blood parameters, growth, and intestinal structure of tilapia reared at 15ppt salinity. In a 60-day feeding trial, fish fed 10⁵ CFU/mL of B. subtilis showed significant benefits, including higher red blood cell counts, improved hematocrit levels, better growth rates and better feed conversion, as revealed by microscopes showing healthier intestinal tissue. Microscope analysis revealed healthier intestinal tissue, suggesting improved nutrient absorption and gut integrity. While white blood cell numbers showed only slight changes, the results suggested the probiotic had a positive effect on the fish's immunity. The results of this study demonstrate that the administration of dietary B. subtilis at an optimal dose of 10⁵ CFU/mL can effectively alleviate the physiological and structural challenges caused by salinity stress, thereby supporting healthier and more productive tilapia farming without the need for antibiotic use.

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