Füsinger Au
The Füsinger Au (also Loiter Au) () is a river in the north of Schleswig-Holstein (Danish: Slesvig and Holsten respectively), Germany.

The Füsinger Au starts north of Idstedt (Danish: Isted), flows through the lakes Idstedter See and Langsee (Danish: Isted Sø and Langesø respectively), passes the village Loit (Danish: Løjt) and discharges into the Schlei (Danish: Slien) near Füsing (a district of Schaalby) (Danish: Fysing and Skålby).