As the titles says, my betta doesn't flare no matter what I do. I've tried the mirror trick. And he has been next to other bettas, of course in seperate bowls. He is as healthy as can be and very happy in his 5 gallon tank. Maybe he's just super chill? Hehe
i also have 1 of my bettas that has never flared i ahve not tried the mirror trick yet, and i plan on doing it at some point. but its my "damaged" betta i call him handicapped. he was in a disgusting cup when i bought him and super skinny. he is still skinny and has unclamped, but never flares and seems to not be as strong of a swimmer. I have had him for awhile now so i think he was probably suspposed to be a cull that never happened. but he eats fine and blows bubbles. so hes alright.
My guy doesn't flare either, he's healthy and spritely, but nothing seems to qualify as competition in his little betta eyes. He's either really really laid back, or just enough of a narcissist (maybe too young, don't know) XD
i had a betta that never flared. for a whole year, he would barely spread his fins.
finally, i put him in a tank beside a female. she had her tank, he had his. and he flared! sometimes, it just takes something special to make them flare. sometimes, they won't ever flare. nothing wrong with it. :B