It must be an epidemic, because mine has it this morning, too. However, Sebastian's whole eye looks like a bubble (or is swollen). He was fine at 2am this morning, but when I looked at him at 9:30am, one eye is bigger than the other. He is in a 1-gallon tank and I change his water once a week. He has live plants, has always been a happy fish, and is a good eater. His water temperature is around 78 degrees. He is still very active and has not lost his appetite. He just has a swollen eye. I have a picture, but I have no clue as to how to post it.
Advice is appreciated!