I have a 1000 gallon fish pond. We had a heron attack a couple days ago. One large white goldfish was found dead with a hole through him near the pond; another found with a similar injury dying on the bottom of the pond. Yesterday we discovered one of our black goldfish with a lot of torn off skin flapping on each side of his dorsal fin. Still swimming around, but slowly. Today he was hanging around on a shallow step in the pond and I was easily able to scoop him up. I've put him a large bucket with some pond salt, some of the pond water and some new fresh water, and an aerator. I took the photo before I'd finished filling the bucket with water. He's pretty active now...in fact he's trying to jump out of the bucket so I've covered with netting. Any suggestions on how to treat him?