AQ salt, warm water, and cleanliness I feel can cure anything.
I got LOTS of misinformation before when I had my mollies. They got infested with ich. Something else, too, I'm thinking internal parasites. I talked to about 5 different people (2 pet store employees and 3 I found to be reliable) and did it all wrong. They were in a 20 gallon and I was told not to clean it out, (except from, who knew?, 1 pet store employee) so I didn't. I just flooded them with medications. And now I'm down to 3 fish and 2 look SO sickly. I lost 4 females. I was told not to use AQ salt, and I kept the water cold. *sigh*
The warm water also helps boost their immune system. The AQ salt definitely lowers their stress (helping boost their immune system) and helps give them "fighting power"! And the clean water helps rid the ich away! (Plus it keeps them happy and comfortable.)
I thought I spotted ich on my female (from switching her around so much) so I immediately washed everything down completely, removed her live plants to a QT bowl, gave her clean very balanced water, and some AQ salt. I kept her water at 82*. After acclimating her and putting her back in, I've never seen her act lathargic nor seen any sign of disease. I'll never know if it was ich or not, but I know I did right by her instead of what happened to my poor mollies!
I hope he makes it, I really do. Losing fish is never easy. Good luck!