I turned on their lights and fed all three bettas this morning before work. They all had water changes last night, and they all ate well this morning, especially my excitable boy, Jackson, who dance and flared at me.
Then, I got home from work half an hour ago and went to feed them their evening meal, and Jackson was curled up on his side at the bottom of his bowl, with a magnificent bubble nest taking up half the surface of his home.
I don't know what happened. All three fish got water from the same source, treated with the same conditioner, fed the same foods. I can't believe it was just his time, considering that he was regrowing his fins so well.
I got so invested in him, since he was in such bad condition when we found him, and he was my first Betta. Honestly, there is no telling how old he was when we found him. :-/ I just know that he had a good run with us, and never went hungry, and was happy.
The sad thing is that I don't even know if something DID go wrong. After all, he was in such bad condition, it could very well be that he had spent the greatest portion of his life at the pet store in that tiny little cup, and I only brought him home in order for him to experience a little more room before his time was up. I went back to that pet store today (to get more water testing supplies) and some of the same Bettas were there today that had been there when I got Jackson, including a dragonscale crowntail they wanted $25 for.