Based on the combination of expert knowledge in aquaculture, the theory of Bayesian networks, and Markov chains, models for forecasting white spot disease (WSD) on black tiger prawns are proposed. These models are built by basing on the pathology,  environmental  factors,  and  biological  characteristics  of  black  tiger prawns.  Models aim to  assess  the infectious status  of  WSD  in  a pond  at  a  specific time, the infectious status of WSD in a pond at adjacent time steps in future, and the possibility  of  the  infection  of  WSD  to  neighboring  ponds.  Using  the  obtained results, the warning about WSD can be informed to farmers soon.