I posted the other week about the fiasco Frida and I had with river rocks in her tank. She seems to be quite happy and normal now, but I came home this morning, and she has what looks like a large piece of dead skin on her chest/belly up to her chin. It seems to be flaking off constantly, and I don't think it's fungus, because her gills are clear, and it isn't 'bumpy', it's all one big white area. Should I be concerned? Could it be bacteria? I'm being very vigilant about water quality, and there's currently minimal ammonia, and no nitrates and nitrites. We had an ammonia spike the other day, because I was forced to be a 100% tank change - could this be it? Is there anything I should do apart from keeping on top of water quality? She seems generally ok and relaxed, it just looks odd, and makes me worry!