Hi I have had discus for almost a year now and they are all doing fine eating and good water qualities. I do a 30% water change every other day and age my water for 48 hours to maintain a stray ph but one of my discus has been sitting at the top corner swimming and eating very little and he is one of my oldest discus but he has a dent in his body and I'm not sure what it is or how to treat it. They get a healthy diet because they're from discus Hans and I feed them Hans discus mix. I have tried just doing more water changes and adding some salt. And unfortunately I can't get any pictures because the dent is not noticeable in photos.