Things You'll Need
The Molly Fish is a type of guppy. A Molly Fish is a live bearer, meaning the babies come out of the mother alive. Breeding occurs easily and often for the molly fish if males and females are in a tank together. Baby Molly Fish will be eaten if kept in the same tank as any other fish (including mollies), so it is important to identify pregnancy in the females. A typical Molly Fish's pregnancy lasts between twenty and forty days and they will have between twenty and one hundred babies at a time.
Watch for any behavioral changes in your female molly fish. Some of the changes in behavior are that she may move slower in the water, stay away from other fish and eat more.
Note if a dark triangular spot has appeared near the anal vent.
Look for the stomach to change. The pregnant molly fish's stomach will begin to grow bigger and stretch out.
View your molly fish throughout the pregnancy. You will be able to detect the eyes of the fry in the molly fish's belly as it stretches, and the spot near the anal vent will get larger and darker.