My clown has dark spots, which he just got recently. The only thing I can think it might be is some sort of fungus. I had a little bit of red slime in my tank, but I cleaned it out. But when I was cleaning the slime my fish was eating at the little bits of red slime floating around the tank. Any advice or comments? All wtaer parameters are perfect now. I think I was overfeeding a little bit before.