The Mooshauser Weir is currently impassable for aquatic organisms such as fish or microorganisms moving along the river bed. Due to local conditions, the construction of a ramp is not possible. The passage is therefore made by a fish ladder. It runs along the bank next to the weir and connects the upper and lower water. Different variants, such as a near-natural bypass channel or a technical fish ladder are being investigated. Structural, hydraulic, ecological and economic criteria are compared for the different variants. The measure is part of the project Agile Iller.