peppermint bristlenose - male or female

Hi all,

another peppermint bristlenose identification post :)

Can female bristlenoses have bristles on their forehead?? I've seen male pictures of brislenoses where the whole head was covered with bristles,
my peppermint is approx 12cm, and has only a single row of bristles going vertically up on the forehead. don't know how many but i think there's under 10 bristles all up. Is this 100% a male? I'm planning to sell it so i need to know asap...
Also, how long or how old does a bristlenose need to be to identify it as a female or male?

thanks
zar

I believe that females can also develop bristles but these arnt as pronounced as the males, still peppermints are suppose to be one of the hardest bristlenoses to sex based on apperance.