I caught ich once, cured it with "general cure" aquarium salt, and raised temp to like 82 or so. I have doubts that was over night, that is a very severe care IMO but good luck.
It doesn't look like it's going to make it mate.
Apart from that, the water can't be fine as the fish's slime coat is stripped...
What's in the water to tread the ich?
Get the medication if that hasnt worked.salt and raised temp
Add salt and raise temp to 82-84 degrees also turn off the light that helped me cure my fish its possible to save him but unlikely.
Get the medication if that hasnt worked.