Anouther thing, are you leaving the mirror up next to the tank? IMO you should only show him the mirror for a shorter period of time (10-20 Min maybe) then put it away.

I am no betta expert though.

Well, you could also try giving him some other things for entertainment. He was probably bored.

BTW, your method worked, but he sometimes still lays on the bottom. He got bored of the mirror after 20 mins but still goes up to it sometimes.

Thanks! ;)

Comet is a good name for a betta IMO.