Exactly whats been said with a couple of additional questions;
What is the PH in his tank?
(depending on what you believe a high ph could cause osmoregulatory issues which in turn can cause dropsy)
Does he suffer any aggression from tankmates?
(hanging head up near the surface is commonly indicitive of stress, normally from aggression)
Does he spend alot of time near the waters surface, more than he used to?
(see previous and also hypoxia is a mild possibility)
What do you feed him and how often?
(high protein diets can cause difficulties with some fish, over feeding can also result in poor environment quality)
Merry is spot on about keeping the tank conditions
absolutely perfect at this time, hospital tank will make this easier if available and depending on the illness/cause keep other fish from risk. This can't be emphasised enough.
If it is early swim bladder then it can be related to many things, bacterial illness being prominent among them. I'd get a bacterial med and use a half dose to start with, on the off chance it is bacterial.
Just noticed your post;Don't rule out swimbladder yet, it isn't a disease in itself and can manifest in a multitude of different ways and for a number of different reasons.
This
is worrying, how long has the tank been set up for? How often and how do you clean your filter sponges, have you treated with any medications recently?
