The enzyme activity of the T-3 group, which was given the highest concentration of probiotic used in this study (1.0 × 106 cfu ml− 1), was not significantly greater than that of the other treatment groups, suggesting that the increased activity of the digestive enzymes in shrimp larvae induced by extrinsic probiotic strains has an inherent limit. Based on these results, the use of a 5.0 × 105 cfu ml− 1 supplement of probiotic in shrimp, P. vannamei, larvae as water additive was recommended. Furthermore, the variation of digestive enzyme activity was investigated at different stages in the present study