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The best discussion we can have on the Japanese Ike Jime technique is to dive into the science of the technique. The gills of the fish have small filaments that they use to breathe dissolved oxygen from the water. The filaments suspend in the water, so when we remove them from the water, the gill filaments collapse. When that starts to happen, the fish struggles to breathe and goes to a stressed state which causes the fish to release lactic acid and cortisol into the bloodstream and into the muscles. The typical way that we keep fish for dinner table fair is to immediately put them on ice, but that does not stop the suffocation process for the fish. The Ike Jime technique is to designed to kill the fish immediately by inserting a spike into the brain area. Since the fish doesn't struggle after this, the toxins are lessened that are released into the blood. The second technique called Shinkei Jime is to use a piano like wire to run through the spinal cord of the fish to destroy the nerve tissue that can residually cause rigor mortis in the muscles of the fish. The final step is to bleed the fish by cutting one or two gills at the base of the gills. After the Ike Jime technique destroys the brain tissue, the heart will continue to be for several minutes which will push the blood through the gills and out of the fish, so you're removing out the toxins that are in the blood. It's recommended that you put the fish in a bucket of water head down for a couple of minutes to allow this process to occur. This can be regular sea water in a five-gallon bucket. And then place the fish in an ice slurry which covers the fish instead of just on top of some ice. 

When you filet the fish at the end of the day, you will notice that the fish is not as stiff as it usually can be, and the meat will be very white and nearly devoid of blood. This provides much better meat for the dinner table.