After fifteen years of fish keeping, I can say that the Molly fish pregnancy cycle is fairly simple.
These freshwater aquarium species are livebearers, easy to breed, and full of energy.
Read on for a complete understanding of a pregnant molly fish.
Molly Fish Gestation
These freshwater fish belong to the Poecilidae family, like other livebearers such as guppies, platies, and swordtails. They have 39 different varieties.
Unlike fish that lay eggs, mollies are livebearers, which means they give birth to live young fish. The gestation period for mollies is one month, but it can extend up to 60 days.
Fertilization
Mollies breed through internal fertilization, a process in which the male fish chase and insets a specialized anal fin called a gonopodium into the female’s vent.
She fertilizes them and carries the eggs inside until she’s ready to give birth to live fish.
Try to keep your pregnant fish in a breeder net before birthing. This provides a safe place for them, free from being eaten by larger fish in the main tank.
Conditions That Affect Molly Fish Gestation
If you intend to breed molly, you need to be careful about some factors:
Water Temperature
When the water is warm, the gestation period is shorter than average. The ideal temperature for fry development is 72-78°F (22-26°C).
Water Quality
Ensure that the water quality is clean and stable for the molly to give birth to a baby fish. Consider a filter or change the tank water to eliminate toxic elements.
Diet
Your molly needs proteins and vitamins to ensure the healthy growth of fry. They also feed on brine shrimp, daphnia, and high-quality flakes and pellets.
Stress
Stress can also affect the gestation period and the fry’s health. Do not overpopulate the tank, and limit contact with the pregnant female.
How To Tell If a Molly Is Pregnant?
These are the signs to look out for:
Physical Signs
You may notice the presence of a gravid spot, an area on the abdomen that shows the eggs. The belly is rounded, full, and, in lighter species, quite translucent.
Dark spots may form on your molly fish near the anal vent during the later stages of pregnancy.
On a light-colored molly, you may find a dark triangular spot near the anal vent. It is called the gravid spot.
Behavioral Signs
During pregnancy, female mollies may appear less active and energetic. These species reside at the bottom of the tank or hide among plants or substrates.
At times, you may see aggression by mollies towards other fish in the aquarium. These creatures have a dominating effect over food or swimming spots.
For some experts, these changes are considered a disease. However, this behavior doesn’t apply to all mollies; some females may not show any visible symptoms until they give birth.
What To Do When a Molly Gives Birth?
Here’s how I care for my pregnant mollies:
Fry Removal: If you haven’t separated the molly beforehand, you can remove the mother molly from a breeding tank as soon as the fry is born to prevent them from falling prey and being eaten.
Fry Care: Feed the fry infusoria or baby brine shrimp until they are large enough to eat flake food. Ensure good water quality in the fry tank or breeding box for their healthy development.
How Often Do Mollies Breed?
Many mollies can store sperm for months. In addition, these species fertilize their eggs every 30 days. Molly’s pregnancy cycle starts with the courtship process and ending with the fry’s birth.
How Many Fry Do Molly Fish Release At Once?
This hardy fish can give birth to 40 to 60 baby fish at a single go. In my case, the birth value reached up to eighty, such as that of the Dalmatian molly.
Final Words
Having a pet molly is the best thing that can happen to you.
Some mollies are already pregnant at pet stores. Be careful when you make a purchase. They are beginner friendly and peaceful, living well within a school.
If you have pet mollies or plan to keep them in the future, ensure they have the appropriate conditions available for breeding.
