Took me a while to look in on this thread, you should have PM'd me.
Anthelminthic
Ant=anti, helminth=worm
A distended belly can be an internal infection or a cestode/worm infection. Luckily many are species specific. The vast majority of wild fish have these and in the wild its not a problem since the shed eggs don't usually reinfect the same fish. But in the aquarium they get reinfected and it can get bad. They usually have complex life cycles with secondary and tertiary hosts. Lucky you...
To cover your bases catch the fish and put it in a QT tank, dose it with an antibiotic AND anthelminthic. Metronidazole and praziquantel are pretty easy to find. I know API makes a product called "General Cure" which is pretty user friendly. Hope this helps.
Oh yeah there is no such thing as a swim bladder, its a GAS BLADDER. One of my pet peeves...take this as another reason to quarantine all new fish.