Dead molly

Question
I just just astblished  my 175gal tank a month ago. I started off with 3 femail
molles witch two looked pregnant. Turned out I fond 9 fry three days later
and there might be more in the dence grass. But the other molley that still
looked pregnint last night was swimming back and forth pacing the tank so
the next morning I put her in a breeding tank inside the 175gl tank. One hour
I fame back to see if there were any fry and she was dead it looked like she
had a simi clear-brown sack comming out near her anil fin. I didn't know if
she side durring labor so I tryed pushing out the sack but it poped and
nothing more than a fluid came our of it. I was just wonderig if it was a  
birthing death or if it could be some kind of bloting disease that I have never
seen a fish die like this.  

Answer
She most probably dies from stress, those floating hatchery's are very very stressful for fish and they have claimed many fish lives, your better heavily planting your tank, and collecting fry when you see them into the floating hatchery things.

Or setting up a new tank and letting them give birth in there then taking them back to the main tank afterwards