Sexing black mollies

[griff5499]

How do you tell male/females black mollies apart? One of my black mollies was sold to me to be male. He is larger and longer than the female. Lately I noticed he/she looked pregnant! She has a low slung belly and she looks squared. Is there a way to tell from the anal fin?
Thanks for your help!

 

[katfishkeeper]

Males have a more pointed anal fin and females have a more fan like fin.

 

[uelissa]

These are on mollies, but it is the same for all live barriers

 

[ldarby1973]

So the platys will be the same way when trying to tell male and female apart