Abstract: An aquarium air pump includes an electromagnetic motor-operated pump unit positioned in the housing of the pump and including two vibrating arms energized by the motor and each carrying a pump diaphragm forming with a closure member of the pump unit casing a pump chamber. Each vibrating arm is positioned on the casing to be pivoted to an operative position to close the respective closure member and a non-operative position in which the arm can be removed from the casing and interchanged. The pump housing includes a bottom part and a top part connectable to each other and sealed in the connected position by a peripheral seal. Cushioning cups support the pump unit in the pump housing to absorb vibrations.