The present invention relates to an apparatus for controlling water temperature and purifying water in an aquarium, which maintains a water (seawater) temperature in the aquarium suitable for the survival of fish in accordance with the temperature of the surroundings, and purifies contaminated water in the aquarium, thereby preventing the fish from dying from unsuitable water temperature and contamination, and ensuring long term survival of the fish. The apparatus comprises: a water chamber for keeping fish in seawater contained therein a water temperature control means and a water purification means for detecting the contamination level of circulating seawater introduced by the water temperature control means and purifying the seawater, wherein the water temperature control means comprises: a water temperature sensor which is disposed on the outside of the water chamber and detects the water temperature a control unit which controls the water temperature detected at the water temperature sensor first and second heat exchangers which control the water temperature in the water chamber based on a temperature signal controlled at the control unit and a four-way valve. According to the present invention, when the temperature of seawater detected by the water temperature sensor is high, the first and second heat exchangers are operated so as to lower the temperature of the seawater, and when the detected temperature of the seawater is low, the first and second heat exchangers are operated so as to raise the temperature of seawater, so that the temperature of the seawater is maintained habitable for the fish. Also, by purifying the seawater by filtering floating materials in the circulating seawater in a filtration chamber, the present invention can keep the fish active and fresh for a long time.COPYRIGHT KIPO 2016본 발명은 활어를 보관하는 수조의 물(해수)을 주변온도에 따라 생존에 알맞는 수온으로 유지함과 아울러 오염된 수조의 물을 정수하여 활어가 수온 및 오염으로 인한 폐사 발생 없이 장기간 생존할 수 있도록 한 수족관의 수온조절 및 정수장치에 관한 것이다. 본 발명은 담수된 해수에 활어를
