I had two adult mollies and one baby from the pet store. Both the adults seemed like female to me but I'm not 100% sure. They have never seemed sick. I woke up this morning to find them both upside down on the bottom of the tank and two new babies swimming around. Why would they both have died and all the babies survive? I don't think it could be the water because the baby that came from the petstore is still fine. One of the new babies has a really puffy stomach like a balloon but the other looks normal. Any help or advice would be greatly appreciated!