The present invention relates to a fish tank in which the overflow system is integrally protruded to the outside surface to purify the water contained therein, and accommodates predetermined sea water or fresh water therein to grow fish or plants, the front plate, the back plate, the left side. The plate, the right plate, and the bottom plate are coupled to each other to form a hexahedral fish tank, the upper portion of which is cut off the upper part of the rear plate drainage step portion to discharge to the outside of the fish tank when water above the water level is introduced into the fish tank And a manure member for blocking a fish or aquatic plant from flowing into the inner surface of the fish tank in which the drainage step portion is formed. Comprising integrally with the drainage tank for receiving the drain discharged through the part, the interior of the drainage tank is accommodated according to the water level Combining configuration of the drain pipe for discharging, and forming at least one through hole in the upper portion of the back plate, and combining the inlet pipe in the through hole, the overflow system for water purification on one side of the fish tank outside of the fish tank Integrally configured to protrude to the side, the utilization of the internal space of the fish tank is expanded than the configuration of a separate overflow system that occupies a lot of the internal space of the fish tank, and the economical efficiency is improved because there is no cost to purchase the overflow system Provide a fishbowl.본 고안은 내부에 수용된 물을 정수하도록 외측면에 오버플로우시스템을 일체로 돌출 구성한 어항에 관한 것으로, 내부에 소정의 해수 또는 담수를 수용하여 물고기 또는 수초를 생육하도록, 정면판, 배면판, 좌측판, 우측판, 저면판을 서로 결합하여 상부가 개방된 육면체의 어항을 구성하는데, 상기 배면판의 상부 일부분을 절취하여 한정 수위 이상의 물이 어항으로 유입되면 어항의 외부로 배출하는 배수단턱부를 형성하고, 상기 배수단턱부가 형성된 어항의 내면에는 배수단턱부로 배출하는 배수에서 물고기나 수초가 유입되지않도록 차단하는 거름부재를 결합구성하며, 상기 배수단턱부가 형성된 어항의 외면에는 배수단턱부를 통해 배출된 배수를 수용하는 배수수용탱크를 일체로 구성하고, 상기 배수수용탱크의 내부에는 수위에 따라 수용된 물을 배출하는 배수관을 결합구성하며, 상기 배면판의 상부에 적어
