Red wag cross Swordtail/Platy female...

Question
I have just acquired a full tank of mixed Redwag Swordtail (red with black fins) and Redwag Platies (same color).
Male are easy to distinguish by the sword, but how do I distinguish females?? I know that the true swordtails are naturally slimmer and the platies more balloon-like and that the lighter red females have a distinct red line down the side to the tail. But I have no way to tell on the intensive orange ones, especially the young one that do not show a gravid spot yet.

Answer
Hello,
Females have no swordtails, and no gonopodium. ( a gonopodium is a penis - like organ)  The males tend to occupy the top of the tank, while the females are usually found closer to the bottom.  
Aquarium salt must be added to the aquarium.  If you haven't done so, it would be a good idea to add salt.  Make sure that you dilute it first, before putting it into your tank.
Lynda