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How Long Are Dalmatian Mollies Pregnant For? Vet-Approved Science & Info

Sarah Psaradelis

By Sarah Psaradelis

Pair Dalmatian Molly

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Dr. Luqman Javed

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The Dalmatian Molly is an interesting type of live-bearing fish that has a characteristically black and white spotted pattern. You can find Dalmatian Mollies with various types of tails. This includes the lyretail, sailfin, and the common variety. Their appearance and tail varieties make them a good choice for tropical and freshwater aquariums.

This type of molly fish is not much different than other mollies, except for their colors and body pattern. This means that the expected time for a pregnant Dalmatian Molly to carry the baby fish (fry) before giving birth is the same as many other live-bearing fish, at around 60 days.

Breeding and raising Dalmatian Mollies is fairly simple, and their ability to adapt quickly to different freshwater aquariums makes them a popular live-bearing fish for aquariums.

Sexual Maturity in Dalmatian Molly Fish

To start, molly fish do not lay eggs as the typical fish would. Instead, mollies give live birth to their young, which are known as “fry”.

The female Dalmatian Mollies become sexually mature and able to reproduce with their species as young as 4 months old, up to 6 months of age. Male Dalmatian Mollies mature quicker and can start reproducing from 3 months old. They reach their reproductive age when they develop sexual organs and are nearly fully grown.

When they are sexually mature, the male and female Dalmatian Mollies will have their fully developed reproductive organs. In males, this includes testes that produce sperm, and a copulatory organ called a gonopodium (a modified caudal fin).

The female Dalmatian Molly has ovaries and a genital opening. Aside from different sexual organs, molly fish are sexually dimorphic. Male and female Dalmatian Molly fish have differences in their appearance, such as males being smaller than females. The female molly will have a rounded belly, while males are slimmer with more prominent fins.

Dalmatian Molly
Image Credit: Eldergeek, Pixabay

Dalmatian Molly Pregnancy

As a live-bearing fish from the Poecilidae family, Dalmatian Mollies reproduce by internal fertilization. The male molly fish will fertilize the females’ eggs inside the body, known as ovoviviparity. The pregnant molly will carry her eggs until they hatch and are ready to leave her body.

Female mollies do not lay eggs, as they only give birth to live fry. The sperm can be stored in the female mollies body for a few months even if she has not recently been in contact with a male. This is a reason why females can be pregnant when you first buy them, or they get pregnant weeks after you separated the genders into different tanks.

Once fertilization has occurred inside a female Dalmatian Molly fish, she will be pregnant for 60 days. However, this period is typically between 50 to 70 days and the Dalmatian Molly will give birth to fry. Most Dalmatian Mollies have between 20 to 80 fry at a time, with 40 being the average.

How Do Molly Fish Give Birth?

After carrying the developing eggs for around 2 months, the pregnant molly fish will give birth. She will typically choose a dark and quiet place in the aquarium to do so. When she is close to giving birth, you will notice your female Dalmatian Molly’s stomach swelling more than usual. Her vent also appears darker in color. Many fish breeders describe this stage as the fish “getting ready to pop” and it means that she is nearing the end of her pregnancy.

During this time, you may notice she is less active and spends more time hiding. It is unusual to see your female molly fish giving birth, as they are great at hiding and choosing to give birth in a dark area of the tank with plenty of coverage. The addition of live plants such as mosses and hornwort is recommended as coverage in a pregnant mollies tank. These plants not only offer female molly security, but it is a great hiding place for the fry too.

Once she has given birth, the parent molly fish do not raise or protect the fry. Most adult mollies will eat the fry. A way to prevent this from happening is by placing the female in a separate tank till before she gives birth, and removing her after she gives birth. With the absence of adults, they are safe from being eaten the adult fish.

Soon after giving birth, the female Dalmatian Molly is capable of getting pregnant again in less than a month, which is why livebearers such as molly fish are such prolific breeders.

dalmation dalmatian molly with bubbles
Image Credit: Eric Isselee, Shutterstock

Breeding Dalmatian Mollies

If you are planning to breed Dalmatian Mollies, the breeding conditions are the same as other species of molly fish. You might want to wait until the female molly is fully grown, as there seems to be a higher success rate at breeding female mollies when they have reached their full adult size. The ideal breeding conditions should be met for the Dalmatian Mollies to encourage them to reproduce.

A good male-to-female ratio of Dalmatian Mollies is necessary, and these fish should be between 6 to 12 months of age. When it comes to breeding Dalmatian Mollies, a ratio of three females and one male is ideal.

Male mollies can easily stress out the females by chasing them around to breed. Having a larger group of females with a small number of males is better, and it ensures that the female mollies are not constantly being harassed. However, you can place a breeding pair of Dalmatian Mollies in a separate breeding tank for a few days.

The ideal breeding conditions for Dalmatian Mollies are warm temperatures at around 75°-80°F (24°-26.7°C). As tropical fish need a heater, you can adjust the heater’s settings gradually till the temperature is slightly warmer.

The pH of the water should be slightly alkaline, between 7.5 to 8.5. The water should be kept clean, with the tank having plenty of hiding places and good aeration for successful breeding.

mating dalmatian molly
Image Credit: JuanCarlosPalauDiaz, Shutterstock


Dalmatian Molly fish pregnancy is the same gestation period as many other live-bearing fish. Dalmatian Mollies are ready to breed at 4 to 6 months of age and remain pregnant for an average of 60 days. After this time the Dalmatian Molly will give birth to between 20 to 80 fry, and the parents do not care for the fry.

Featured Image Credit: Joan Carles Juarez, Shutterstock

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