Swollen belly

Question
Hi samantha,
I have two  male bettas which are kept in separate parts of the tank.  They both at times have a swollen bulge emerge just behind their gills.  Sometimes it flares up (it is much more prominant in one betta over the other) and then it will go back down to normal by, say, the afternoon.  They look as though they have eaten too much or that they are pregnant (but they are both male).  At first I thought I was feeding them too much so I have cut back on their food, but it is still ocurring.  It becomes swollen at random times, not even after specific feeding times.  They both still seems relitively healthy, bright and active and their water is clean most of the time.
thankyou
jessica

Answer
Hi Jessica,
I'm not sure what this could be but it could just be they want to fight and are trying to show off at times. Also it could be that the food isn't the best quality for them. If you don't have it already try nutra-fin or tetra flakes.
I hope I've helped,
            Samantha