Aquaculture has made significant strides in providing a sustainable and efficient protein source. However, bacterial infections such as those caused by *Streptococcus agalactiae* and *Aeromonas veronii* remain a persistent challenge, affecting the health and productivity of Nile tilapia (*Oreochromis niloticus*) fingerlings. This study aimed to assess and compare the efficacy of two bivalent inactivated vaccines administered through different methods: oral vaccine followed by an oral booster (OR+OR) and immersion vaccine followed by an oral booster (IM+OR).