The invention relates to an aquarium comprising a water tank and a sieve that is arranged in the water tank; the sieve comprises a filter and a driving mechanism supplying power to the filter. The filter is disposed in the internal part of a container of the water tank, while the driving mechanism is disposed outside the container of the water tank. Consequently, the invention can effectively allow the power source of a conducting wire of the sieve of the aquarium to avoid getting into the container of the water tank; in addition, it can eliminate the possibility of electric leakage of said conducting wire underwater in the container of the water tank.