I have 3 female mollies, 2 of which I am almost positive were or are pregnant. I wasn't planning on separating them out for the birth cause I have plenty of plants and hiding spots in my tank. A few days ago they were so plump in the belly it looked like they were going to burst but now they are looking fairly thin. I have bred mollies before and usually have been able to tell if they have given birth or not but the ones I have now don't look as thin as I would expect them to be after giving up their fry. Is there anyway to tell? I want to vacuum my gravel but don't want to suck up any little ones.