The molly is among the easiest of all aquarium fish to breed. Mollies are livebearers, bearing their young live instead of laying eggs like other fish do. As long as you set up your breeding tank properly, you can breed your mollies and raise the fry successfully. Mollies are an excellent choice for beginning hobbyists, in part because they are so hardy and easy to raise.
Remove the parent fish as soon as the fry are born. Those larger fish can mistake the tiny fry for food. You can use a bare tank, or a tank with only a few plants, to raise the fry. Avoid using power filters, since the relatively large holes in the intake tube could suck in the fry.
Feed a small amount of fry food to your mollies two or three times a day. The amount you will use depends on how many fry you have, but squirting out an amount about the size of your fingernail should be enough.
Watch the fry carefully as they feed. Remove any uneaten food as soon as you can so it does not foul the tank.
Supplement the commercial fry food with fresh food like newly hatched brine shrimp. You can buy a brine shrimp hatchery and brine shrimp eggs at the pet store. Pour the newly hatched brine shrimp into the tank with the mollies and allow them to feed. There is no need to remove those brine shrimp, since the mollies can eat at their leisure.