Mittelfischbach is a municipality located in the district of Rhein-Lahn within the state of Rhineland-Palatinate in western Germany. It serves as a local administrative area situated in the regional landscape of the Rhine-Hunsrück region.
The municipality belongs to the association community of Aar-Einrich. It functions as part of the local governance structure providing communal services and infrastructure for its residents within the state's western territory.