||Mud crab is a potential aquaculture species with the characters of fast growth and great tolerance of environment stress. In addition, mud crab is a kind of high valuable and popular seafood widely distributed in the world. In Taiwan, the production of farm mud crab is top one among reared crabs. According to the data shown by Fisheries Yearbook Taiwan Area, the production and value of mud crab is in a range of 185-247 tons and 40-70 million, respectively, in the period 2005-2008 in Taiwan. However, the production and value of mud crab was decreased sharply from 247 tons and 70 million in 2006 to 170 tons and 36 million in 2009, respectively. Disease outbreak is one of the causes leads to the mud crab production drop. Disease problem of crab aquaculture is more serious at the time near harvest which can not be controlled by drugs as well as shrimp. Incidences of crab diseases are the consequence of the interaction of crab health, environment and pathogens. Therefore, disease prevention could be achieved with improving host healthy status and environmental conditions. In the project, we are going to cooperate with mud crab farmers to find out the cause of disease outbreak through surveying the environmental conditions and disease during the culture period. In addition, the probiotics can improve the healthy status of shrimp and grouper will be prepared and provided for mud crab farmers to better the disease problem, and then the feasibility of disease improvement by the probiotics will be evaluated. It is hoped that the developed technologies will be beneficial to improve the problems of disease in mud crab aquaculture, consequently increase farmer’s income.