I have barrels of goldfish to keep down mosquito populations on my dads farm. We got some gold fish to put in there and I go out and take care of them. I was checking in on them and I saw one glint with white spots in the bottom. Half an hour later I caught the lil dick in a barrel so deep I have to stick my head under to reach the bottom, and he has three white spots on his tail. . I am treating with kordon rapid cure. What else do I need to do. I can't add heat, or oxygen. What can I do to fix this. I dont like it, but I guess if this fails its all feeder goldfish i could euthanize them all and start over. I bet I got him sick, because my other barrels are doing great.