In the mud crab, Scylla serrate (Forskal, 1775) cultivation, the adult crab behavior patterns, such as daily and reproductive activities, need to be addressed and determined, especially under control conditions. This information can be used to plan mud crab hatcheries intensively. Thus, the current research was carried out to discover the behavior and daily activity of the mud crab (S. serrata)  under control conditions. A survey was conducted using observation technique and systematic recording towards some behavior phenomenon of used 4 (four) adults of the mud crab comprised one big and small males;  one big and small females, observed in an aquarium with a volume of 1.5x1x1 m³.  The data obtained were tabulated in the form of tables and graphs, then described.  The result showed that the daily activity of the mud crab from the highest to the lowest was the repose (resting) activity (51,88%), followed by the movement (45,70%), the agonistic activity (2,30%), and the lowest activity was represented by feeding  (0,12%), respectively. The reproductive activity was not found until copulation and was only observed during seduction and mutual running.