Dissolved oxygen may be generated by adding a peroxide to a fluid stream and then catalytically decomposing the peroxide to generate oxygen. As the peroxide is catalytically decomposed, the oxygen may solubilize in a surrounding fluid so as to provide dissolved oxygen. In some examples, the amount of peroxide added to the fluid stream is controlled such that substantially all of the hydrogen peroxide added to the fluid stream catalytically decomposes and yet the dissolved oxygen concentration of the fluid stream does not exceed a dissolved oxygen saturation limit for the fluid stream.