Pond Boss Forums POND CONSTRUCTION Creating habitat Otter-proof safe havens for fish

I am having the same otter problem, I killed four in 2 days during the winter. They have gotten a lot of my fish I am afraid, before I shot them. I am thinking of trying an electric fence so it doesn't happen again and I have power. I was told put one strand 6 inches off the ground and another strand 12 inches. What is the best spray to use to keep the grass out of the fence and not risk hurting the fish in the pond? I tried traps and Konobear traps 2 of them and the only thing I trap is turtles. Any other ideas would be appreciated.