To me it looks like he got roughed up. Are there tank mates that would attack him?
Keep water nice and keep him fed. Keep an eye out for an infection. I don't suspect anything to be seriously wrong because he is swimming fine, but just keep a close eye on him.
Keep water nice and keep him fed. Keep an eye out for an infection. I don't suspect anything to be seriously wrong because he is swimming fine, but just keep a close eye on him.