in lakes limited to a about half dozen meters or so in depth of course deeper estuarial waters often have an even more sharply defined thermocline to be drawn upon in this manner such control of temperature enables warm water fish and even other types of marine animals to be raised or 34 grown out 34 likewise air lift provision of water for the head end of raceways according to this invention has an added advantage over screw propulsion without air lift in enabling smaller propellers to be used at even lower speeds thereby reducing electric power requirements and costs injection air lift in transferral of fish from one raceway to another or to a harvesting location is superior to prior art methods because the fish essentially swim from one place to the other without interposition of net or human hands or other handling device minimizing injury raceway apparatus for use according to this invention preferably floats in the surrounding body of water thereby eliminating or minimizing the need for anchoring adjustable supports such as the illustrated tracks between raceways and their flotation means or the suggested roll up means for the flexible raceway material are helpful in enabling the depth of water in the raceway to be decreased as when adding or harvesting fish or to be increased as when the growing fish require more volume this invention facilitates life cycle culturing of fish from fingerling size to marketing size in a single facility thus a batch of fingerlings of appropriate quantity and type is placed in a raceway appropriately adjusted in depth so that its volume confines the fish to the desired density as the fish grow.