We evaluated the effects of probiotics on the non-specific immunity and antiviral capacity of . We fed groups of shrimp ((live) plus 1% Bacillus firmus (live), or 1.0×10⁸ CFU/g (inactivated). The control groups were fed a non-supplemented diet. Each diet was fed to triplicate groups of 60 shrimp that were reared in aquaria. We randomly selected 10 shrimp per group every 5 d and measured a range of humoral immune parameters (superoxide dismutase SOD, acidic phosphatase ACP, alkaline phosphatase AKP, nitric oxide synthase NOS and lysozyme UL) in each individual. The shrimp were challenged with white spot syndrome virus (WSSV) after two weeks. We then calculated the cumulative mortality of each experimental group. Supplementation with bacteria significantly increased serum SOD, ACP, AKP, and NOS compared with the controls. There was significantly lower cumulative mortality in shrimp that were fed the probiotics diet (10.7%, 39.3% and 26.2%, respectively) compared to the control (64.28%). Our results suggest that supplementing the diet with shrimp intestine probiotics improves immunity and the antiviral capacity of .