I know this might be a silly question, but how can you tell if a balloon molly is pregnant?

I have a black female in my tank. I have heard one way to tell is some kind of black spot on the stomach which are the fry, but since mine is black I can't see. She already had one batch of fry about three weeks after I brought her home. I found only one of the fry which I named Junior but the poor little thing must have been eaten. Anyway since she always looks fat because of her shape, is there any other marking to tell if she is pregnant? The reason I am curious is that I am planning on getting one of those breeder nets soon so that I can save the fry, and I'd like to know when I should put her in.

There's a male marble molly in the tank which I purchased at the same time who constantly follows her around, so I expect more fry in the future. Btw I have had these two fish about 3 months now so how often can I expect her to drop fry?

:lol: I saw these for the first time on the weekend and I thought exactly the same thing :laugh: :laugh:

As soon as I saw them I knew I had to have one! They are so cute! Mine sort of reminds me of a bird flying around in the tank because her mouth looks like a beak. Last night everywhere she moved the male molly was right next to her. It must be annoying. I just hope she drops more fry sometime...