Before I start, I would like all of you to know that I know that I have made a huge number of mistakes, and I really am a complete beginner at taking care of fish.
Now, to introduce my fish, he is a male 5 year old (about) orangish-pink veil tail betta. His full name is Boo Radley (named so by his previous owner, my sister).
His first owners were our neighbors who were moving and gave him to us. They kept him in a clear, 1 qt. bowl with marbles in the bottom and fed him when they remembered. They cleaned his tank with water that they let sit out for 24 hours, and I don't think this was done a lot.
He was then given to my sister who kept him in the same bowl, but as far as I know, she fed him every day. She didn't clean his bowl a lot and when she did, she used distilled water.
After I continued to pester her about the care of her fish (no, I was not knowledgeable, but I didn't like to see fish treated like that either), she finally gave him to me. Honestly, now that I look back on it, I was not much better than her. I kept him in the same bowl he'd always been kept in. However, I did feed him every day, and I changed his water every 3-5 days with treated water, not distilled or 24 hour sit-out water.
My little sister had another betta who was in a 1 gal. tank with a filter, hood, light, gravel, thermometer (stuck to the side) and barrel caves. However, the filter was too strong and was tearing his fins. We didn't know about filter baffles, so we just removed it from the tank and I cleaned the tank a little more often. Anyways, this betta, Pickles, died due to a tank cleaning mistake (that I beat myself up over many times over).
However, after Pickles died, we now had a "bigger" tank that he could be moved to. This happened about half a year ago. So, we moved Boo to this 1 gal. tank and he seemed to like it a lot. Before, he'd only eat about 1-3 fish pellets every day, but he began to eat 3-6 in this tank, which we were happy about. I got him a moss ball, because I figured it would help keep his tank clean, which it has, somewhat. I would have gotten him a bigger tank, because I knew bettas needed more space than 1 gal, but I wasn't allowed to.
However, about 7 weeks ago, Boo stopped eating. He'd done this before with my sister and had gotten over it in about 2 weeks so, I didn't really start worrying until 2 weeks had passed. After that, I tried feeding him freeze-dried bloodworms. He wouldn't even touch them. I didn't really try anything else. I just kept cleaning his tank and feeding him (even though he wouldn't eat).
Then, after about 2 more weeks, he started swimming along the gravel. He could be sideways, or even upside-down. He would rest vertically, with his nose in the gravel which really scared me, and when I called my local pet store to explain my problem, they just said that 5 years was old for a betta and I could keep trying to feed him, but he would probably just die soon.
So, 2 more weeks passed, and Boo still hadn't eaten but he still had the "swim away" instinct when I would catch him with my fish net to clean his tank. So, I figured he still had the will to live and I wouldn't begrudge him that. I really didn't want to euthanize him yet.
However, over the past week, I've finally begun to read up on bettas and I found many things that I did wrong in the beginning and I've been trying to right them. I tried feeding Boo small bits if thawed peas, and I've even tried feeding him frozen daphnia, but he refuses to eat. I've given him Epsom salt baths (1 tsp. per gallon) twice, because his symptoms seemed most to fit with constipation. Then, I cleaned his tank last night and he didn't try as hard to swim away as he normally does and when I saw him trying to swim towards the top of the water, he had to struggle a lot. Since it's been 7 weeks since he last ate, and because I can no longer think of anything else to do, should I put him down? I've been looking up euthanasia for bettas online, and if I do euthanize him, I think I'll try to use the clove oil way. Should I euthanize him, or is there something I've missed? Please help!