Fish recirculating aquaculture water treatment tank

The invention discloses a fish recirculating aquaculture water treatment tank which comprises an air flotation tank, an ultraviolet sterilization tank and a dissolved oxygen supplement tank, wherein the air flotation tank, the ultraviolet sterilization tank and the dissolved oxygen supplement tank are sequentially arranged; a first wall is arranged between the air flotation tank and the ultraviolet sterilization tank; the air flotation tank and the ultraviolet sterilization tank are mutually communicated through a water flow passage at the bottom of the first wall; a second wall is arranged between the ultraviolet sterilization tank and the dissolved oxygen supplement tank; the first wall and the second wall are shorter than the circumferential wall of the fish recirculating aquaculture water treatment tank; the fish recirculating aquaculture water treatment tank is characterized in that a water level control device is arranged on the second wall; the water level control device comprises electric control equi