Iki Jime (活き締め?) or Ike jime (活け締め?) is a method of paralyzing and bleeding fish to maintain its quality. The technique originated in Japan, but is now in widespread use. It involves the insertion of a spike quickly and directly into the hind brain thereby causing immediate brain death. A fish brain is usually located slightly behind and above the eye. When spiked correctly, the fish fins flare and the fish relaxes, immediately ceasing all motion. The blood contained in the fish flesh retracts to the gut cavity, which produces a better coloured and flavoured fillet. This method seems to minimize the pain.
With experience you can easily notice the difference between a fish prepared with the iki jime technique versus other methods. With iki jime, the flesh is clearer and tends to be softer. When the fish is eaten raw, it is really pristine and has kept all its inherent qualities as the blood has not infiltrated the meat. The suzuki pictured above will be served in two ways side by side, sashimi and seared.