Introducing New Fish

Question
Hello, I was wondering if introducing new fish to an aquarium (20 gallon) that
has a pregnant molly in it will cause the molly enough stress to attempt to
abort her pregnancy? She was probably 3 weeks into her pregnancy and the
introduced fish were a male and female swordtail and two black mollies (not
sure on sex).

Thanks for your help

Answer
I've never seen that it's had that big of an impact in my experience. I certainly wouldn't worry about it.  If you have already done it, I'd be surprised if you said there were any problems.

Just remember, if the molly is not in a breeding net when she has the fry, there is a chance that the fry will get eaten.  These little guys are quite smart though and can quickly find "hiding spots" so long as you provide plenty of cover!

Good luck.