Abstract: The invention relates to a device for cleaning aquarium windows (5), in particular the inside thereof, comprising an internal element (1), which can be positioned on the inside of the aquarium window (5) and has a surface (Ib) directed towards the inside of the aquarium window (5), and also comprising an external element (2), which can be positioned on the outside of the aquarium window (5) and has a surface (2b) directed towards the outside of the aquarium window (5), wherein the internal and external elements (1, 2) attract one another under the action of magnetic force, in which case movement of the external element (2) along the aquarium window (5) causes the internal element (1) to follow this movement. The device is characterized according to the invention in that at least one cleaning edge (3) is arranged on the surface (Ib) of the internal element (1), this surface being directed towards the inside of the aquarium window (5).