delta tail bettas

[danny]

hey, i found out that 2 of my 3month old betta fry are delta tails!i can't remember though who their mother was.the father is veiltail(i actually let the fry grow with the male as i have higher survivors than separating them).but judging from the color,i think it's from my 1st long finned female betta.

unfortunately,they are both male.
uhm,since most female bettas have short fins,how can you know if they are a delta or a plakat?is there really a way?

[Suzie Q (Lori)]

I still have trouble telling female apart...BUT count rays on a female's tail rays...3 or more is a delta. PK have a distinct anal fin (again...im not good at telling PK apart from other female).