It all started a few weeks ago when I noticed Fuji becoming lethargic and unresponsive. He used to dance when he saw me and get super excited about food, but he stopped dancing and seemed disinterested in food. I noticed that he appeared to bloated, so I thought he may be constipated and tried to feed some pea. He also appeared to have some slight pine-coning, and I was really scared that he may have dropsy. Later I noticed what appeared to be a lump on his left side, just under his fin, and I thought perhaps it may be a tumor. I changed his water and lowered the level so that he could swim to to the surface more easily. When I changed the water I saw that a piece of his skin and scales had fallen off. When I checked Fuji, I saw that the area where the lump had been was now an open sore. I've started treating the water with a Lifeguard All-in-one-treatment. Fuji's energy levels have picked up and he has stared dancing again when he sees me and is excited about his food again, but the wound doesn't seem to be improving. In fact, over the last few days it looks like it's swelling and looks really nasty. Fuji is resting a lot at the bottom of the tank and sometimes lies a little sideways. Anyone have any idea what this open wound may be? This has been going on for about 2 weeks now.