To identify probiotics that promote the growth of largemouth bass and enhance their resistance to largemouth bass ranavirus （LMBV），this study isolated Bacillus and Lactobacillus strains from the intestines of largemouth bass.The strains were selected based on hemolysis tests，antimicrobial susceptibility tests，enzyme production，acid production experiments，as well as colonization experiments in the largemouth bass intestine .Finally，5 strains of Bacillus subtilis （BS04，BS49，BS58，BS66，and BS74），2 strains of Bacillus amyloliquefaciens （BA04 and BA12），1 strain of Enterococcus faecalis （Efa01），and 5 strains of Lactococcus lactis （LL01，LL05，LL09，LL13，and LL22） were incorporated into feed respectively and administered to largemouth bass for 30 days to evaluate their effects on growth performance and resistance to LMBV.The results showed that BS04，BS49，BS66，BS74，BA04，BA12，LL01，LL05，LL09，LL13，and LL22 significantly increased the percentage weight gain and specific growth rate of largemouth bass，while significantly reducing their feed conversion ratio.The expression of 4 immune factors （IFN-γ，IL-1β，IL-8，and TNF-α） in the spleen and head kidney of largemouth bass in the BS04，BS49，and LL01 groups was significantly increased.The viral load in the spleen and head kidney of each experimental group was significantly reduced after the LMBV challenge，and the relative protection rate was higher than 20%，with the highest relative protection rate observed in the BS04 group at 55.1%.In conclusion，Bacillus subtilis BS04 isolated in this study can effectively improve the growth performance，immune response，and resistance to LMBV in largemouth bass，demonstrating its potential as a feed additive.