"Ikejime (活け締め) or Ikijime (活き締め) is a method of slaughtering fish to maintain the quality of its meat. The technique originated in Japan, but is now in widespread use. It involves the insertion of a spike quickly and directly into the hindbrain, usually located slightly behind and above the eye, thereby causing immediate brain death. When spiked correctly, the fish fins flare and the fish relaxes, immediately ceasing all motion. Destroying the brain and the spinal cord of the fish will prevent reflex action from happening; such muscle movements would otherwise consume adenosine triphosphate (ATP) in the muscle, and as a result produce lactic acid, making the fish sour. Furthermore, the blood contained in the fish flesh retracts to the gut cavity, which produces a better coloured and flavoured fillet. This method is considered to be the fastest and most humane method of killing fish."
- Raising the Quality Bar - by Brown & Kelly