An aquarium system for aquatic organisms capable of easily performing maintenance of a purifying device and a circulation pump, etc., and downsizing a purifying zone is provided. The system of the present invention includes an aquarium 1, a partition wall 2 dividing the aquarium into a nurturing zone 11 and a purifying zone 12, a circulation pump 81 for circulating water between the nurturing zone 11 and the purifying zone 12, and at least one purifying device selected from a filter 50 for filtering water by making the water pass through a filtering material, a protein skimmer 70 for removing proteins contained in the water by making the proteins adhere to air bubbles, and an ultraviolet light irradiator for sterilizing the water by irradiating ultraviolet light to the water. The circulation pump and the at least one purifying device constitute a unit member. The unit member is mounted on a mounting frame to thereby form a purification unit 3. The purification unit 3 is accommodated in the purifying zone 12 in a removably inserted manner in a state in which the unit member is mounted on the mounting frame.
