Nah that looks like the scales becoming white and starting to wound up. I moved the rtgg from an 720L tank to my 3200L tank. And he attacked every fish in my big tank so i had to move him back again. After that this **** turned up about two weeks ago. It looks like the scales starting to fall of. Ive tried salt but that wont help out at all.
Wow, i remember you saying a few weeks ago that you were moving him and hoped your move went like mine, trouble free. Obviously yours is a bit of a bad un. Mine's still as good as gold, no trouble whatsoever.
I have no idea what that patch is then. I suppose it's a case of keeping your water clean and monitoring.