Look for the female's eggsack...a mature female should have a round tummy where the eggsack is full of eggs...then look for the vertical stripes display on my females...when they're are full of eggs their vertical stripe is displayed when they flare. You also look at the finnage and some say the head of a female looks a bit sharper compared to a male.

I've an upcoming spawn with pretty good hmpk and i'll post some pictures when i've taken them.