I know for a fact that it was lack of attention that was stressing him out. He has every bit of his color back, he has stopped shredding his own tail, and right now he's sitting on top of one of his plants just looking at me, as content as can be. Every once in a while, he'll get up and dance for me, then flare at Koenig for a while, then come back to rest and look at me again. He's even stopped getting constipated.
I came back from class, and for some strange reason, all hell had broken loose. Sakana bit off another little chunk from his tail, and he and Koenig were trying to bit each other through the divider. I can't figure these guys out. Anyone have a degree in fish psychology?
I left Sakana where he is, because I know the attention from me is helping him. I switched it so that Diamond is back in the middle, and Koenig is on the other end. Diamond doesn't pay attention to any other fish, so maybe peace will be restored.
So far, so good. Koenig is still trying to pick fights with Diamond, but Diamond isn't paying any attention, so I'm sure Koenig will calm down soon. Diamond is just swimming around, perfectly oblivious to the fact that he has two other fish next to him. Sakana got bored with trying to pick fights with Diamond, so now he's playing in the flow of the filter.
That should help. Sometimes they get a little carried away and see fins and don't exactly realize they are their own when they're flaring at another Betta. They just figure the other Betta let his guard down, so they better chomp down on those fins before they get away.
Silly boys! Putting Diamond in the middle should help. Eventually, Sakana will realize that Diamond isn't interested in playing the same games Koenig did, so he'll give it up.