The way most Japanese fishing companies actually do this is a process called Ikejime . There are a few different ways to do this but they are all basically the same cause brain death and/or paralysis in the fish in a specific way, in order to keep the fish fresh. Kaimin Katsugyo which uses acupuncture to keep fish alive but docile, this seems to be much more of a speciality thing though which does make the fish caught this way rather valuable. Fish caught this way are usually sold to higher end sushi restaurants. Although with this method I can't find any documents produced by actual fisheries that use this method. One actual Ikejime method recommended by the Asia-Pacific Economic Cooperation (APEC) Fisheries Working Group for air transport is: a cut is made toward the front of the flatfish severing the major artery and the spinal cord. Placement of the cut is made to preserve the greate