I was going to say 'as a side note' but considering it relates to my original question...
My female molly is pregnant. Looking at her this morning, she has a large squared-off belly and darker coloration. I assume this would probably explain the mood swings, eating, aggression and hovering by the heater I've been seeing. Unfortunately she also has white ich spots present on her fins. She must be under tremendous stress. I don't have a second tank yet so I am getting something to separate her. Hopefully she can stick around and get to be a good mom.