The invention provides a deep-water fish farming system comprising a fish cage of controllable buoyancy having one or more chambers, which can be submerged and refloated at a controllable rate to any depth. A winch mechanism mounted preferably on a platform that covers a section of the cage releases and gathers a cable connected to a sinker. When the combined weight of the system overcomes the buoyancy, the fish cage is submerged to a depth determined by the effective length of the cable between the winch mechanism and the sinker, with the sinker touching the sea bottom. The submerged cage is refloated to the surface by remotely activating the winch mechanism, thus releasing the cable, while keeping the sinker on the sea bottom. When the cage is refloated to the surface, the buoyancy is increased to allow pulling of the sinker from the bottom. The invention further provides a method for submerging and raising a fish cage at a controlled rate to any desired depth in deep water.