betta fish fat stomach

Question
I have a male betta in a single environment. Last week his stomach got very round. He gets fed Tetramin Tropical Granuels(3 in the morning and 3 in the evening) as per the pet store. I also have another betta in an identical environment getting the same diet and he shows no such signs.  

Answer
Hi Grace,
 Your fish probably has dropsy. It's not that serious because it's not really a disease yet but it can turn into one so you should take care of it. I'll give a website that can help you with doing that.
http://www.tropicalfishcentre.co.uk/Diseases1.htm
      I hope I helped,
          Samantha