pregnant molly

I just purchased two mollys yesterday for my youngs sons. One is a balloon molly and the other one well, isn't...it's longer and more slender. I'm not certain which one gave birth last night to 11 young ones but there are only 3 left in the tank. The balloon molly was the one I had first thought was pregnant but now I'm uncertain as the longer, more slender fish is very slow-moving today. We actually expected it to die today but it's hangin in there! The balloon molly keeps poking at it too. So, with that long-winded story, where is this so-called spot that a pregnant molly posesses? I'm curious who the mom is.

Moving stress could account both for the lethargic fish and all the little ones. The birthing process for a live bearing fish is much different than that of a mammal. The eggs develop inside the female, but they are nourished by their yolk sack, not a placenta. The female just expels the fry when they are mature or when she is stressed. Immature fry will still have some of their yolk sack. Both egg laying and live bearing females have a somewhat distended tummy when they are full of eggs. It shows more on live bearing fish, which can have a very full tummy and a large dark area next to their vent. Your so called slim fish could be a male, and if you want to save the fry, give them a dense clump of floating plants.