Antonio the maker says: If the fish is be released, the  duty of the angler is that this should be done in such a way (possibly without taking the fish out of the water, or having to grip the fish) that the fish will neither be additionally stressed nor injured and once released can remain alive. If it is difficult because the hook is embedded in an inconvenient place (for the fish), then it is generally advisable to leave the hook where it is and cut the line.