The development of tilapia culture in China has been affected by streptococcal disease, of which Streptococcus agalactiae is the main pathogen (Liu et al., 2014). Traditionally, antibiotics were often used to control fish diseases, but the abuse of antibiotics can lead to the increase and spread of drug-resistant pathogens, resulting in ecological imbalance (Dawood et al., 2018). As such, prohibiting the abuse of antibiotics appears to be the current social consensus, and China is even implementing a policy of 'antibiotic free farming'. In such context, the search for feeding of additive bacteria to enhance disease resistance for healthy cultivation of tilapia is of considerable significance.