rbishop, I would think that losing both of his eyes could mean aggression, not water conditions, although good conditions will keep further infection away, I am wondering if these has been some aggression on your fish. based on your descriptions, I think you have a black moore goldfish, and since they do have bulging eyes, maybe it was a great target for some of the other goldfish. Since goldfish are pretty agressive. They tend to pick on eachother. sometimes relentlessly on one particular fish. I would reccomend quarantining it if you have one. If not, you should get a quarantine tank to keep any sick or injured fish in.