Could Something Be Wrong With My Mollie?

[jumpupforjoy]

noticed one of my balloon mollies belly is getting bigger and she hides alot aswell only had her 3 weeks and she had a black spot on her side rear at the back and wondered if anything as wrong?

 

[greenscooby]

I'm no expert, but from what i've read online she might be pregnant, someone will correct me if i'm wrong.