Whitish/translucent Patch - Should She Stay In Hospital Tank?

[daizeUK]

My 18 month old platy Clarabel has been in the hospital tank for over two weeks now, since I saw a small whitish patch on her left flank just behind her head.  I thought it best to isolate her in case it turned out to be columnaris.  I've been treating the hospital tank with salt and some Pimafix.
 
She has been acting healthy and active the whole time, showing no symptoms except for the white patch (which appeared to be subdermal and not a superficial fungus.  More like an ulcer under the skin).
 
The patch now appears to be healing, it is still visible but translucent rather than white.  It's probaby quite hard to see in the picture:
 

 
Can I return her to the main tank now or should I keep her isolated longer?

 

[fm1978]

Has anything else been going on in the tank out of the ordinary? Could it just be a discoloured 'stress patch'?
 
Sure doesn't look like columnaris. How about another week in solitary, since it's already set up, and see what happens from there?

 

[daizeUK]

Nothing obvious that would explain the sudden appearance of the patch, no new additions to the tank, no stress factors.
 
There was a rescape in her 64L tank but that was a whole month before the white patch appeared, water parameters have been fine since.
 
I've had some mild cases of what appears to be cottonmouth in my 120L tank and I initially wondered if it might be a result of cross-contamination between the tanks.  That's why I was worried about columnaris, as cottonmouth is a form of columnaris.  The symptoms aren't the same though, I've checked her mouth carefully and there is no sign of external fungus.

 

[Mamashack]

She's a lovely Mickey Mouse!
Can't advise on the when as I have no experience with it, but I hope she continues to progress well and you can put her back in her tank soon!

 

[fm1978]

I think it would be a gamble to put her back in then if you've ruled out stress. And if it were me, I'd probably not take the gamble until the patch has healed.

 

[LyraGuppi]

My guppy female has had this for a month or two now. She shows no discomfort, as you said, and it isn't spreading. She is a bit loony, but all guppys are like that, I suppose. I left it alone, and it seems to be getting clearer.

 

[daizeUK]

She's a lovely Mickey Mouse!
Can't advise on the when as I have no experience with it, but I hope she continues to progress well and you can put her back in her tank soon!

 
She's one of my first original fishies, turning into a bit of an old lady now but she she a lovely vibrant orange when she was younger.  She's had lots of lovely babies including several grown-up daughters that I keep in my 64L
 

I think it would be a gamble to put her back in then if you've ruled out stress. And if it were me, I'd probably not take the gamble until the patch has healed.

 
It might be an injury, especially since I introduced some new woody branches into the tank when I rescaped.  Maybe she scraped herself going under one of the unfamiliar branches.  I hope that's all it is.  If there's still a risk it might be disease though I'll continue to keep an eye on her like you suggest.
 

My guppy female has had this for a month or two now. She shows no discomfort, as you said, and it isn't spreading. She is a bit loony, but all guppys are like that, I suppose. I left it alone, and it seems to be getting clearer.

 
Good news  Hopefully mine is the same!