Finding the brain: where to spike a fish
The brain sits just behind and slightly above the eye, and hitting it cleanly is what makes ikejime instant and humane. Learning the landmark for each body shape is the skill that separates a clean spike from a miss.
The basic landmark
The brain of most fish is small and sits just behind and slightly above the eye. A common way to find it is to follow a line up from the eye and back from the pectoral fin until you feel a soft spot. That soft spot is your entry point.
It shifts with body shape
The exact spot varies with the shape of the fish. Round-bodied fish, flat fish, and long elongated fish all carry the brain in a slightly different position relative to the eye. Study a few of each type and the pattern becomes easy to read.
How you know you hit it
A correct spike causes an immediate flare of the fins and a distinct color change across the body. If the fish keeps thrashing without that response, you missed the brain and should reposition. With practice you feel the give of the soft spot before you commit.
FAQ
What if I keep missing on a certain species?
Body shape is usually the reason. Flatfish and elongated fish hold the brain in a different spot than round-bodied fish, so adjust your angle and landmark for that shape.
How do I confirm the fish is dead?
Look for the fin flare and color change right after the spike. Those are the signs the brain was struck and death was instant.