Experimental ponds of about the same size as small scale farmers' ponds (one to several hundred square meters susrface area). These ponds are upwelling because they are built into the water table. With fertilization and/or supplemental feeding, they can be quite productive, but they are impossible to drain and completely harvest. Using off-bottom net pens with a large enough mesh to allow nutrients and oxygen in and wastes out would solve the harvest problem. These ponds have guards so stealing fish should not be a problem.