Once the flatfish have been immobilized, they can be packed in a standard wet lock box lined with expanded polystyreneorinone of the new stackable expanded poly styrene systems. In the systems, flatfish are placed in shallow expanded polystyrene boxes with drainage holes in the bottom. Coolant is used in each of the boxes to maintain temperature. These boxes are then stacked (usually) three deep. The bottom box is a receiver for drip from the boxes above. Allowing for drainage helps to ensure that the flatfish are not packed in bacteria laden drip.