To gain knowledge on the movement of various diadromous and potamodromous fish species, an acoustic network in the River Scheldt, its tributaries and connected canals was established. The River Scheldt and its largest tributary the River Lys are the main waterways, yet they are connected with various canals. The water flow in this system is highly regulated by mainly weirs and shipping lock complexes. Consequently, fish are likely not able to freely move in the river basin. Yet, to facilitate fish migration, fish passages have and are been developed. Therefore, this network will allow to evaluate the effectivity of these fish passes and how fish use the river basin throughout their life.