Looks like it may have bloat. The abdomen looks really distended
At this point there is probably not much that can be done.
The normal treatment would be to add some epsom salts (Magnesium sulfate)
to the water and to soak its food in a solution of epsom salt, but I doubt seriously that it will eat the way it currently looks.
I keep looking at your picture . Could you post a couple more pictures. Maybe one looking straight on. These fish are very prone to getting bloat especially if they are feed a high protein diet to much and to often.
But this fish may have dropsy. I can't tell from the one photo.