I am not good with disease identifying, but whatever she has it is probably in the tank already. They don't like nitrates up high, mine begin to stress quickly and lose color between 10-20 ppm. The general hardness seems to be a bit hard for GBR's to me, and some seem able to temporarily adapt to harder water better than others. It doesn't look like she is bloated from the pictures, but it is hard to tell. If she is eating, then she still has the will to live, so putting her down at this point would be a bit unfair, but that is just my opinion. It does sound like a fungus, but, again, I am not good with these things. Hopefully someone can give advice on how to treat it.
edit: Mardel Maracyn seems to be the one to treat external fungal infections, so that may be worth looking into.
Last edited by chevyguy8893; 02-27-2013 at 02:32 AM.
Reason: added info