Molly's?

[MikeyMain]

Hi, i am 14 yrs old so please dont flame me if this is a dumb question.

I have a Fluval 1000 tank and have 2 comet fish,9 zebra danios,2 algae eaters,3 white mollys,2 black mollys,2 red eye tetras, 3 silvertip tetras. I recently just bought a breeding tank (its the little one with the v-insert) so when the time comes for baby fish i know what to do..but recently i discoverd 2 little fry having a swim in the corner of the tank, im sure they are white mollies, but when i look at the mollys there are no signs of pregnancy, one of them is quite thin and small and has a few greyish/black dots, the medium sized one is just well medium sized and there is a big fat one but no signs of pregnancy, one of my black mollys looks quite fat but theres no dots etc..(the small white molly follows a black molly around)and recentley the fry have disappeared(probaly into the plants). My questions are,

1. Why is there only 2 babies?
2. How can i tell which fish they are from?
3. How can i keep the fry till they grow bigger?

P.S, I will have pics up of my tank and my fish (and the fry if i can find the wee rascals)

Thanks in Advance,
Mikey

 

[SMSBrunetteGirl]

Well,the mother probably gives birth every 1 month or something like that and the other grown fish may have been eating the newborn fry