Woke up this morning to find one of my Dalmation Mollies with Pop Eye. Do I have to worry about this happening to the other fish. I read that I should do a 50% water change. But the weird thing is...This happened to the fish after I did a water change of about 30%. 1 hour after the change, I checked my parameters and found nothing to be out of whack.. 0 ammonia, 0 nititrites, 10 nitrates, stable pH of 6.8.
Should I just keep on eye on this fish or move him out of the tank? if so, what meds do i need to give him?

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