The present invention relates to the water treatment technology in aquaculture, and is especially one pure oxygen aerator for high-density fish culture. The aerator includes one section of cylindrical pipe, one section of gradually expanding truncated cone and one section of gradually reducing truncated cone bottom, which are connected successively to constitute one sealed container. Inside the container, there are one aeration unit connected to oxygen pipe and water draining pipe in the bottom stretching beyond the container. Inside the sealed container, oxygen can dissolved repeatedly without escape and this results in high oxygen solubility and low power consumption. |