The Chinese mitten crab (Eriocheir sinensis, CMC), one of the worst invasive species in the world, has been causing ecological and economic damage in European water bodies. This led to the launching of the Clancy project, which generally aims for establishing effective management strategies to mitigate the impact of CMC. In this project, multiple traps that were especially designed for catching CMCs will be installed in various water bodies in the wider North Sea region in order to monitor and to reduce the CMC populations. In this context, this specific study aims to investigate and to optimize the performance of the CMC trap in terms of the hydraulic characteristics in its near-field. Therefore, a 3D numerical model was created and operated based on the CFD software OpenFOAM. The specific study area selected for this investigation is the fish bypass at the Zwalm River in the southern part of the Belgian province of East Flanders. A test case was simulated under steady flow conditions to analyze the flow pattern around the trap. The results of the study can contribute to the optimization of trap placement and design in order to maximize their efficiency in managing CMC infestations.