An aquarium system for aquatic organisms easily performs maintenance of a purifying device and a circulation pump and downsizes a purifying zone. The system includes an aquarium, a partition wall dividing the aquarium into a nurturing zone and a purifying zone, a circulation pump for circulating water between the nurturing zone and the purifying zone, and a purifying device selected from a filter for filtering water by making the water pass through a filtering material, a protein skimmer 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 purifying device are mounted on a mounting frame and are accommodated in the purifying zone in a removably inserted manner.
