It's not unusual to lose some of the fry right after they are born. My Molly's last batch was 60. 20 died the first day. She had bred with an orange balloon belly. I only ended up with 10 that are now juvys. What I found odd was that none of the fry were black. All of the ones that made it either had only natural color or a mixture of orange, black and natural.
I fed mine on crushed flake food.
Congrats! I hope these continue to grow.