This chapter presents the decision support tool (DST) for simulating the impacts of selected management actions on the ikan bilih fishery. The selected management actions are unsustainable fishing efforts on the fish stock and the effects of water level regulation on the fish’s habitat. Further, we also elaborate on the methods to determine no-catch zone areas and simulate water level regulations on the flooded rice field. We combined a hydroacoustic approach with maximum entropy models (MaxEnt) to estimate the absolute abundance and current standing stock. Then, we engaged the Schaefer Surplus Production Model (SSPM) to simulate the impacts of fishing gear regulations on the fish stock fluctuations. Again, MaxEnt model combined with ArcGIS 10.5 was used to measure the effects of water level regulations on the availability of the fish habitat. We overlaid the lake’s topography, bathymetry, and baseline map in ArcGIS 10.5 to simulate the influence of water level management on the extent of the area of flooded rice fields. Based on the simulations, a water level of 362.5 above sea level and restrictions to 100 lift nets (bagan) are highly recommended, highlighting the importance of the continuation of the previously advised management responses like reduction of lift nets. Further, we propose several areas as no-catch zone areas, particularly on the eastern area of the lake, where natural barriers occur.