Vortex oxygen-dissolving device for water tank

Disclosed is a vortex oxygen-dissolving device for a water tank, comprising a retainer, an oxygen-dissolving unit comprising a stirring assembly and an oxygen supply turbine assembly, an isolation chamber, and at least two fastening devices. The retainer is set at an open top of a water tank and comprises a plurality of radial ribs and at least two mounting portions formed on an outer circumference thereof. The stirring assembly comprises a hollow shaft and at least one blade set. The isolation chamber is arranged inside the water tank and adjacent to a circumferential wall thereof. The isolation chamber defines an interior space for containing a floating ball set and forms a plurality of apertures in communication with the interior space. The oxygen supply turbine assembly comprises a circumferential ring body and a blower body. The fastening devices are arranged vertically and symmetrically between the retainer and a stand of the water tank. As such, easy and efficient installation can be realized.