Immune response of saline tilapia (Oreochromis niloticus) to feed enriched with probiotic Bacillus amyloliquefaciens at high salinity

Tilapia is a widely favoured fish due to its substantial meat content and appealing taste. The incorporation of probiotics in tilapia farming can enhance the fish's immunity against diseases. Additionally, probiotics can increase the total protein content of the feed and maintain the balance of digestive microbes. This study aimed to investigate the immune response of saline tilapia fed a diet enriched with the probiotic B. amyloliquefaciens at a salinity level of 10 ppt. The research focused on
various blood parameters in tilapia, including total erythrocytes, leukocytes, and hematocrit levels, as well as the food conversion ratio (FCR) and specific growth rate (SGR). The rearing method involved maintaining approximately 100 g of tilapia fry for 45 days, with four treatments and three replications. The treatments included a control without B. amyloliquefaciens and additions of the probiotic at concentrations of 10³, 10⁵, 10⁶, and 10⁷ CFU/mL. The study results indicated no statistically significant differences (P>0.05) in FCR values (1.16–1.24) and SGR (2.03–2.24% BW/day). However, the addition of B. amyloliquefaciens at a concentration of 107 CFU/mL led to an increase in erythrocyte count and hematocrit levels during
the study period, with no observed effect on leukocyte count in saline tilapia reared at high salinity.