Abstract: A combined aerating and filtering device includes a filter box to be mounted on the side wall of an aquarium for carrying filter material through which water from the aquarium will pass to be filtered. A combined filter pump and air pump assembly is supported by the filter box and includes a housing, a motor carried within the housing, an air pump carried in the housing and driven by the motor and a filter pump driven by the motor. An air outlet is carried by the housing and connected with the air pump to thus provide means for aerating the aquarium. The filter pump extends into the filter box to draw water from the aquarium through the filter material within the filter box, and to return the filtered water to the aquarium.