Yes swimming and eating as usual.It could possibly be a parasite, but it looks more like an injury to me, personally. I would suggest quarantining him if at all possible in case it's something that could spread. Is he otherwise behaving normally? Is he swimming okay? Eating okay?
Thanks. Appreciate the advice!Doubt that he's sick then. Perhaps it's just a mild injury or benign growth. If you notice his swimming ability declining or he stops eating well, quarantine and treat him with salt. He seems okay for now, though. Just monitor him closely