In order to generate waves in a volume of water (12) of an aquarium, it is proposed that a storage container (22) which extends beyond the surface of the volume of water (12) should be provided in the aquarium (10). Using a pump (32), water is periodically pumped from the water container (10) into the storage container (22) and returned from the storage container (23) into the aquarium (10). The energy delivered to the water during this leads to fluctuations in the position of the free surface (14) of the volume of water (12) and in-phase operation of the pump (32) provides stronger surface displacements in the aquarium (10), which are comparable with a wave in open water and which expose the plants and living beings in the aquarium to an alternating mechanical load.