My original plan was to introduce my double tail betta, Delfino, to my community tank of platies and cory cats. I floated him I'm his cup in the tank and he was utterly freaking out. He would not stop flaring!
I decided not to risk it, and took him out. So next I try my veil tail, Captain. While he was floating, he did not flare once. He was curious, but not flaring. Finally, I released him, and while he chased the platies a bit, he wasn't persistent and he never flared.
I'm watching them VERY closely. He flared at my bumblebee platy a bit. If one of them gets in his line of sight, he'll swim after them, but never for more than a second or two, and he doesn't flare or snap his jaws.
He has lived with tetras before, and had the same behavior. For the first couple of days he would chase them, and after that he never seemed to notice them. Since it hasn't been 24 hours yet, I'm optimistic :)