In September, my betta of around 1 1/2 passed away. I had perfect parameters at the time during this situation, a lot of which was handled on reddit. I thought it was constipation so i fasted him and fed him peas. Yet the bulge would not go away and would grow and shrink as I did various treatments. I then gave him epsom salt baths and it went down slightly. I continued the treatment for 3 days, but due to him being very skittish and after it looked a little less than what it was originally i stopped treatment and it ballooned back in size. I then started to give him more epsom salt rounds that didn’t work and then gave him a blue dip than did nothing. He was still able to swim and did not show any sign of being unhappy other then looking tired from the large belly and long fins. He eventually took an extreme pitfall where he could not move from the bottom of the tank and couldn’t swim up more than an inch or two in front of himself. I ordered melafix and the other parasitic seachem medicine but it did not arrive on time and he passed away in his tank. It deeply upsets me to this day not knowing about if this was a tumor or a swim bladder issue. He was the betta that made me love the hobby and got me through a tough time and I still think about him to today. If anyone could help identify what happen and maybe give an insight to his demise. Swim in peace Ponyo 
thanks for posting pics, he was beautiful! I hope someone with more experience will be able to comment and give you a possible resolution or explanation
