Hello all, I am having some trouble with my 4 month owned veiltail Betta, Baxter (rescued from Petco). About 3 weeks ago I noticed that he was not passing any feces and seemed to start growing around the abdomen area. I usually feed him pellets because he is a college fish and it is easily accessible and attainable to me. I take him home during long weekends, but on normal weekends I just let him fast and not eat for two and a half days. He currently lives in a 4 gallon hex tank with three live crypt plants and is heated to 78-80 degrees Fahrenheit, roughly. It is also filtered and I always change the water when i come back after the weekend; I take out about 2 gallons and re-add and reheat the new water before placing him back in. About a month ago, I noticed some slight fin rot, so added aquarium salt to his water for the first time, and it cured the minor rot fully. I continued to add a lower amount of aquarium salt just to condition the water, and this is when i really started to notice the problem. Since then, he has not pooped, and I have tried several methods. I have stopped feeding him pellets completely and started to fast him for 3 days, giving him peas on the third day. I noticed that was not working, so I then placed him in a half gallon Epsom salt bath with a teaspoon of Epsom salts in it. He seemed to not mind that, and I placed him back into fresh water. Today, I did another water change of about 75% and did not add any aquarium salt to his water and also tried to feed him the fibrous part of the pea, which he rejected. Other days he has eaten the pea, but today and yesterday he did not. I also grabbed a mirror and let him flare his gills for about 2 minutes before letting him relax. What I am confused about is this: he is still extremely active, not sluggish or slow, and he seems almost normal besides for his bloated belly. What could be his problem, or how could I possibly fix it? I am a biology major in college, so I am not too afraid of big answers or complicated responses to this question. I can also attach pictures of him if necessary for diagnosis or curiousity. Thank you for your time in advance!