Here in New Orleans, lots of critters eat our fish. Raccoons, egrets, herons, cranes all tear through our ponds, eating fish and having a water lily salad with their sushi. As much as we might want to shoot egrets after losing a prize koi or goldfish, it is illegal. It does, however, seem to be perfectly OK to shoot humans and we do it daily, reducing the human population by at least one daily. But I digress.
Years ago, a client of mine was at his wit's end. Egrets were dining daily on his goldfish. This man was a sensible, middle aged guy, a successful and caring OB/GYN who cured, not harmed living things. But he had had it. One day, he got a shotgun and shot at the egrets while they were enjoying dinner. He missed the egrets. But he did manage to puncture his liner, mangle his lawn furniture and his neighbors fence. Luckily he was not caught by the local law enforcers; I don't think they would have understood.
Soon after, I talked him into Gator Guard, a pretty effective way of scaring birds and other critters away.