molly swimming nose up

Question
Hello!
I have had my aquarium running for 2 weeks.  It is a 29 gallon with 2 mollies, 2 platies, 4 guppies, and 11 tetras (19 fish).  I also have 2 live plants (a forget the type of grass that it is).  I got the tetras and 2 guppies first and the mollies, platies, and 2 guppies about a week later.    
My question is about one of my black/white spotted mollies...I've had her for a little over a week.  I know she is female and she appears very pregnant (her abdomen is huge and she is kind of square ventrally).  On Sunday she started to swim funny.  every few minutes she goes vertical (nose up) and hovers like that for about 3 seconds before she is able to right herself again.  She eats, poops, and acts normally otherwise.  From my knowledge swim bladder disease causes them to go nose down, so what do you think is wrong with my fish?
Water chems and temp is all normal.
Thanks for your time!

Answer
Hi Belisa!

It sounds like she is just suffering with swimming with her overly large belly. Swim bladder usually causes your fish to lie on their side alot so it doesn't sound like she is suffering from that. A couple of my Molly's do this routinely and they are perfectly healthy. My advice, just keep an eye on her to make sure she doesn't have any other drastic changes in her behaviour, if she doesn't then I would just put it down to  overly large belly.

Hope this helps!

Cheers!Rach