So, I’ve had this pleco for coming on about 6 years now . He has grown to about 8 inches . Today I got home from work and he was hidden in the corner like normal. I happened to look at his tail and he had no skin left it looks like it’s just straight bone . Also there are parts on his skin that seem to be peeling off. I just recently lost 5 of my 6 goldfish in this tank and I did a full water change and treated it . One other thing to add . About 3 days ago I woke up in the morning to only my goldfish in the tank . After further investigation, I found my pleco behind the tank. He jumped from where the filter sits at the top of the tank . This was the first time this had ever happened and he wasn’t out of the tank for long . As soon as I put him back in the tank he started swimming normally. Any help is appreciated TIA.