Make a loop around your safety slide or however you tie to the arrow. Make a loop at the end of your string coming from your bow.
Stick the loop from your bow under and through the loop on the arrow.
Pull the loop from your bow all the way through the loop on the arrow to the tip of the arrow. Put the tip under and through the loop.
Pull the arrow all the way through the loop.
Pull tight.
Very simple to unhook and rehook the arrow to the main string. Knot will never come undone but will never tighten.
If the arrow goes all the way through a fish, just quickly unhook the arrow and pull the main string through the fish then rehook the arrow.