The present invention relates to a device for oxygenating water in aquaculture plants for marine organisms in the sea, together with a method for using the device. The invention provides for the supply of substantially pure oxygen which is distributed via a specified system to the water. Here given devices arrange for the formation of oxygen microbubbles with an oxygen partial pressure which is such that the oxygen passes into the water in the aquaculture plant. The distribution of oxygen is adjusted in relation to the water's oxygen saturation.
