Four feeding trials were conducted to evaluate the effects of dietary probiotics as antibiotic replacers in Japanese eel Anguilla japonica , Nile tilapia Oreochromis niloticus , and whiteleg shrimp Litopenaeus vannamei . In the first experiment, growth performance, non-specific immune responses, immune-related gene expression and cumulative survival rate of Japanese eel fed Bacillus subtilis WB60 (0.5× 10 7 CFU/g ) with mannanoligosacharide (5 g/kg) was significantly higher than those of fish fed control (CON) diet. However, there were no significant differences with the oxytetracycline (OTC) diet. In the second experiment , growth performances, non-specific immune responses, cumulative survival rate of Nile tilapia fed B. subtilis at 1 × 108 (CFU/g ) and Lactococcus lactis at 1 × 108 (CFU/g) diets were significantly higher than those of fish fed CON diet. Immune-related gene expression and enzyme activity of these diets were significantly higher than those of CON and OTC diets. In the third experiment, growth performance , non-specific immune responses and cumulative survival rate of whiteleg shrimp fed B. subtilis at 1 × 108 (CFU/g) and L. lactis at 1 × 108 (CFU/g) diets were significantly higher than those of shrimp fed CON diet. Immune-related gene expression and histology of shrimp fed these diets were significantly improved compared to those of shrimp fed CON and OTC diets. In the fourth experiment, g rowth performances, non-specific immune responses, immune-related gene expression and cumulative survival rate of Nile tilapia fed B. subtilis at 1 × 108 (CFU/g) , Enterococcus faecium 1 × 107 (CFU/g), and E. faecium 1 × 108 (CFU/g) were significantly higher than those of fish fed CON diet, however, there were no significant differences among fish fed the probiotic and OTC diets . B ased on these results, B. subtilis at 10 8 CFU/g , E. faecium at 10 7~8 CFU/g , and L. lactis at 1 × 10 8 CFU/g could be ideal probiotics in terms of the growth performance, immune responses, enzyme activity, disease resistance and gene expression, to replace antibiotics in Japanese eel, Nile tilapia, and whiteleg shrimp.