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.