Re: Pearlscale Goldfish disease - please help!! :(
#2
It may be that the black moor is displaying mating behaviour with or bullying him. However, if he's still cowering in a separated section/tank, something is still awry. I would:
* let us know the tank results in the main and isolation tank for ammonia, nitrite and nitrates, using a liquid-based test kit - it's paramount that results are consistently 0, 0 and <20 (or <20 above tap water nitrate levels) respectively if there's to be any possibility of healing (irrespective of whether medication is used);
* course of action if required
https://www.fishkeeping.co.uk/articles ... mmonia-nitrite-spike.htm;* from what you describe and the photo, it's almost certainly not swimbladder disorder or whitespot, but possibly fungus or bacterial infection secondary to a bullying/mating injury; for that reason, I'd buy some eSHa 2000 and dose it *if the water quality results above are all fine* (if they're not, the water quality issue itself is more likely the crux of the problem and addressing it ought to resolve it);
* only once he's back to normal behaviour and healed, return him to the main tank.