The gestation period for mollies is generally about 4 weeks. Mollies are livebearers and can sometimes carry their babies longer than average.
Many people are dismayed to learn how many babies the molly can produce. It is not uncommon for this species to become pregnant shortly after giving birth. Mollies can give birth to more than 60 babies at one time and remain fertile for up to 3 months after delivery.
Female mollies can be differentiated from males by the shape and size of their anal fins. The male's fins will be slightly smaller and more elongated than the female's. To prevent babies, it's important to separate the sexes.
To raise the baby mollies, separate them from the parents shortly after birth. The parents will eat the fry if given a chance. A breeding tank or net should be used in this case.