My fat little Badis fish, what could be the problem?

I have a Florida flag fish with exactlly the same problem. In her case I believe it's because she seemed to lose her taste for algae and sinking wafers and instead just started hanging out at the surface at feeding time and ate whatever I fed the other fish.
 
Well.. After talking with a guy at my local fish store and from what I have seen, my fish does not have bloat.

2+ Months being in this condition of fatness
Eyes are not bulging out of her head.
No protruding scales from the body.
She is one of the most active Badis fish in my fish tank.
She is always the first to eat and likes to eat more than the others.
She is still very fast when swimming away from being spooked or chased around the tank.
No heavy breathing.

Basically there is nothing wrong with my fish, except that it is over weight compared to all the others. Maybe a rare case of fish being over weight, but it is not Bloat or dropsy.
If this decease was so fatal I would not think my fish would be this active and healthy after 2 months.

I put her in a sick tank for 3 days with a male to see if anything would happen with there behavior, all they did was sit at the bottom and turn pale in color. So I put the male back into my tank and his dark color came back within only a couple Min's. The fat female was very pale in color and doing nothing in the tank at all, kinda like she was slowly dieing from being in the hospital tank. So, I put her back into the main tank and her color came back within 10 min and she's doing great.

Here's a picture of her today. Very healthy and does not have bloat...

I suppose it's easier to see a fat fish and call Bloat/dropsy then to actually figure out what the problem really is...

bigfish.jpg
 
AquariaCentral.com