<；P>；PROBLEM TO BE SOLVED: To provide a new filtration system for improving the occupancy area of a live fish tank to a whole water tank and a water tank equipped with this filtration system. <；P>；SOLUTION: Two or more filtration chambers are arranged at the lower part of the bottom of a live fish tank, and filter mediums are arranged in each of the filtration chambers, and those respective filtration chambers are made to communicate so that when circulating water passes through each of the filtration chambers one after another, the water may pass from the upper face to lower face of the filter mediums, or from the lower face to upper face of the filter mediums in each of the filtration chambers. <；P>；COPYRIGHT: (C)2011,JPO&INPIT
