Well fly fishing in general is an activity that requires a good amount of coordination and practice to do well. For Williams specifically, I think it was essen

Well fly fishing in general is an activity that requires a good amount of coordination and practice to do well. For Williams specifically, I think it was essentially him applying the same perfectionism, discipline and scientific approach to it as he did to hitting a ball. Back to your question, I think its about "sportfishing"–that is, going after certain fish with certain gear, fishing in tournaments, holding records, etc. It's a thing (see https://igfa.org/ https://igfa.org/)