I have never used booze for killing fish
. After bringing the first tuna aboard we learned to put them into a bucket head
first to eliminate the blood spatter. I favor the sharp knife behind the eyes in the center of the head
. Most certainly bleed the fish
for good quality. Cutting the tail and trailing the fish would be a good alternative, until a shark got on to it. Don't worry about the blood too much, just don't let it dry. Ripping a gill works well.