How do you tell if a black Molly is pregnant?

She'll be incredibly fat and look like she's bloated.

I had a dalmation molly and she would get so fat for a while before popping out all those fry.

If your molly is pregnant, she'll give birth more than once, they actually give birth several times before running out of the sperm they stored and do so over a few months.

If you want to keep them make sure you scoop them up and put them in a breeder net before the adult fish get a chance to eat them.

you can tell when a fish is pregnant its Extremely fat fatter than the rest.

if it's been with a male once period