When cutting large red fish, there are many useful “tricks” from which you can cook very tasty dishes. One of them is Julien “Marine”.
So.
Use a spoon with a sharp “nose” to scrape the fish from the head, spine and all large fins.
I spied this “trick” in restaurants in Japan. They don’t lose a single piece of fish, just like in Italy from pork. They have their own “part” prepared for each piece of ink – everything is in motion, nothing is wasted.