The present invention relates to an aquarium formed to hold and raise an aquarium fish. The present invention relates to an aquarium equipped with a circulating filtration bath, formed to allow water in the aquarium to be circulated by a natural circulation method. According to the present invention, the aquarium allows water to be filtered while being circulated in filtration tanks arranged plurally and a filtration bath, thereby having an effect of naturally improving water quality. In addition, the filtration tanks and filtration bath are arranged to allow a complex filtration apparatus to be optionally installed according to a water tank environment that a user prefers, thereby allowing a little freer water tank environment to be created. The filtration tanks are arranged to be formed on both sides of a water tank, and the front and rear surfaces of the water tank are made of a transparent material, thereby allowing an aquarium fish to be viewed in the front and rear of the water tank and securing improved appearance. The water tank comprises only an aquarium fish and a water plant therein, and devices for filtering water are built in the filtration tanks, thereby allowing an appearance improving effect to be increased. In addition, a plurality of storage tanks are arranged, and the storage tanks perform a function of storing extra water so a shock to an aquarium fish can be minimized in a changing process of water. Furthermore, an environmental change applied to an aquarium fish can be minimized by using the storage tanks even in an injection process of various chemicals and a water quality improver.본 발명은 관상어를 수용하고 사육하도록 마련되는 수족관에 관한 것으로, 수족관 내의 물이 자연순환방식으로 순환될 수 있도록 조성되는 순환식 여과조가 구비되는 수족관에 관한 것이다.본 발명에 의하면, 다수로 마련되는 여과탱크 및 여과조에서 물이 순환하며 여과되도록 함으로써 자연스러운 수질 개선의 효과가 있다. 상기 여과탱크 및 여과조는 또한 사용자가 원하는 수조 환경에 따라 복합적인 여과장치를 임의로 설치할 수 있도록 마련됨으로써, 좀더 자유로운 수조 환경 조성이 가능하다. 상기 여과탱크는 수조의 양측면에 형성되도록 마련되고, 수조의 전후면이 투명한 재질로 마련됨으로써, 수조의 전후면에서 관상어의 감상이 가능하여 미관이 개선되는 효과가 있다. 상기
