Here's what happened. About a week and a half ago, we discovered that our (What the pet store calls "Gold Sucker Fish") had tail rot and was hanging out by the place where the air comes out of the undergravel filter. Well we took the carbon out and used MelaFix to fix his tail rot and hopefully help out with whatever was wrong with him. He was medicated for a week as indicated on the back of the bottle, and his tail rot went away. This morning I looked at him, and it's all back again, his tail looks like it's just wilting away. And now he hides *ALL* The time, he didn't come out of this neon cave house we have in there at all yesterday, and when he does come out he doesn't come out to suck on the glass or anything, he just sits on the filter bobbing around being pushed by the bubbles and landing again. He seems quite ill but I don't know what could be wrong with him. It's almost as though he's lethargic. Any suggestions? I feel as though he's in misery, everyone else in the tank seems fine. Any suggestions please reply.