Not too sure,
but if its a male it may be a Plakat,
if female i'd say SuperDelta
how big is he? looks to be a young delta tail(at this point not superdelta-not enough 'spread' in his tail. if it is a young fish he might have some growing to do in those fins.
also could be female as others suggested but the ventras are fairly long? as asked above-does it have a 'beard' when it flares? if not, a nice delta girle.
lovely color..ive got one just like him!
cheers
the betta in question:
he is surely fully grown at 2 inches. when he flares, if his tail fin makes a 180 degree spread, then id guess hes a halfmoon plakat(hence his short fins). anything less than 180 he is a delta tail PK(ive never seen dtpk, but i guess its possible).
both bettas are very lovely!
cheers.