How Long Does It Take a Molly to Give Birth? The Ultimate Guide

As livebearers, molly fish give birth to live young ones rather than lay and hatch eggs. Considering this type of breeding, a molly fish parent may wank to know; how long does it take a molly to give birth? 

A molly takes an average of 45-60 days to give birth. However, this period varies among the individual fish depending on their genetics and environmental factors like water temperature. The female molly takes about 24 hours to give birth to all her fry

In this article, I’ll discuss molly fish’s gestation period and how long a pregnant molly takes to have all fry out of the belly. Keep reading! 

The Molly Pregnancy Process

Understanding the molly pregnancy process from conception, embryo formation, fry development, and pre-birth to the actual birth is vital. Let’s explore the process in detail. 

1. Conception

Conception will always be simple, effortless, and fast once you have male and female mollies in a conducive environment. Being livebearers, mollies reproduce sexually. 

Generally, the male deposits sperm into its female counterpart through the anal fin or gonopodium. A gonopodium is a modified anal fin that male mollies use to transfer sperm to a female’s genital opening during mating. 

The delivered sperms eventually fertilize eggs within the female. Successful fertilization leads to conception. 

Note that a female molly can store sperms for future retrieval and usage. So, even without a male in the tank, your female mollies can still conceive and become pregnant.

Find Out: Why Do Mollies Die After Giving Birth? The Solution

2. Embryo Formation

After fertilization and conception, eggs form embryos within the female molly’s body. During this time, embryos obtain essential nutrients from yolk reserves found in the eggs before fertilization. 

Also, nutrients can be mobilized from the maternal tissue resources to supply the embryos with sufficient nutrition. To that effect, you should enhance your fish’s feeding routine to supply these nutrients. 

This stage of pregnancy is complex and crucial. Hence, you should always monitor and analyze your fish’s nutrition needs to ensure she’s fed properly with the right feeds during this early development. 

You can guess this stage of molly pregnancy by observing the fish’s underbelly. A fish that started developing embryos will have a relatively darker mark under its belly. This area is called the gravid spot, a tell-tale sign of a pregnant molly. 

Actually, the gravid spot helps you differentiate between a pregnant molly and one that’s just become fat. 

3. Embryo Development into Fry

The third stage involves the embryos changing form into little fry larger than the embryos. The changes are usually prominent within 20-30 days after fertilization and conception. 

At this stage, your molly fish shows signs like; 

  • A swelling belly 
  • Behavioral adjustments are also visible. For example, unusual loss or increase in appetite 
  • Restlessness 
  • Some mollies change coloration 

When you notice these signs in your female molly, know she’s probably been pregnant for about a month. 

4. The Pre-Birth Stage

Next to embryo development is the pre-birth of the fry. By this time, your female molly shows obvious pregnancy symptoms, including; 

  • A swollen belly that’s almost square. 
  • A visible gravid spot. You may also see live fry in the belly of the mother molly. 
  • Isolation patterns indicate that the fish is just about to give birth. 
  • Reduced movements

These signs inform you that you should now prepare for the impending younglings. Soon, the molly will give birth, and you shouldn’t be surprised. 

5. The Birth Process

Finally, it’s the birth time. Birth of fry is the ultimate goal of both you and your molly. This only happens once the fry have fully developed. 

The fry comes out as a live and free-swimming fish. On average, it could take 1-24 hours for all fry to be delivered. So, you should be patient and don’t panic if you notice any delays in the birthing process. 

The moment the fry are outside, they are on their own. Mollies don’t have parental care, just like most other fish. 

In fact, if the mother stays in the breeding tank, she starts preying on the fry. So, you must remove her from the tank. Doing this increases the survival rate of your fry. 

After birth, the fry can freely swim and feed. Hence, the aquarium should have proper nutrition, such as high-quality crushed flakes, freeze-dried foods, and pellets. 

Below is a table showing selected molly fish species and their gestation periods. 

Species Gestation period
Dalmation molly60 days
Common black molly30 days
Black sailfin molly40 days
White sailfin molly21 days
Black lyretail molly60 days
Molly Fish Species and their gestation periods

Signs Your Molly Is Close to Giving Birth

When your molly is about to give birth, there are imminent signs you will always notice. These could be both behavioral and physical. So, be on the lookout for the following symptoms.

1. Increased Abdomen or Belly

Generally, the shape of the belly gets extremely swollen. This is an indication of the growing fry inside the molly’s stomach. 

As these fry increase in size and form, they cause their mother’s belly to extend, even becoming more squared towards the final gestation days. An increased or swollen abdomen indicates that your fish will give birth in just about a week. 

2. Darkened Gravid Spot

Molly Fish Gravid Spot

A gravid spot appears as a triangular-shaped area located near the anal vent of the molly, as shown above. It’s a reproductive feature that shows your fish’s status in terms of reproduction. 

The appearance of the gravid spot can inform whether your fish is about to release fry or not. When you see a more prominent or a darker or opaque gravid spot, know it’s almost time your molly gives birth. 

Thus, the gravid spot color changes due to the embryo’s development inside the belly. Usually, it comes from a light gray transition to almost black when the fry is practically ready to come out. 

3. Fry Have Visible Eyes

In some cases, it’s possible to see the eyes of the fry through the pregnant molly’s skin. When you see this, it indicates that the little fry is now fully grown – awaiting birth. 

As the fry grows, their features become obvious, developing into more elaborate structures. With careful observation, you can watch fry features such as the eyes, which are usually visible thanks to the molly’s outstretched, translucent skin. 

If you want to better see the fry’s eyes, you should improve the tank’s lighting conditions. That said, adequate lighting enhances visual contrast. Hence, you can effortlessly see the unborn’s eyes. 

All said, the ability to see the eyes of the fry through the pregnant mother’s skin shows the pregnancy is later stage. 

4. Loss of Appetite    

For some reason, your molly fish could lose appetite, therefore eating less food than usual. This is only a temporary appetite loss, which is normal for some mollies approaching labor. 

In general, the growing mass inside the female molly’s belly can exert pressure on the fish’s internal organs, including the digestive system. Somehow, this increased pressure makes the female uncomfortable and lose interest in food. 

Additionally, appetite loss may be vital in helping your fish naturally prepare for labor. 

5. Behavioral Changes

Behavioral changes can determine whether your pregnant molly is about to give birth. Towards the end of its gestation period, the molly could depict the following behavioral changes; 

  • Seek seclusion 
  • Reduced activity 
  • Spend more time in hiding 
  • Lose interest in food. 

Monitor your fish to provide the best care during this time. 

How to Prepare for Molly Birth

You can prepare for molly birth by first ensuring the pregnant molly is housed in a separate breeding tank to avoid disturbance from other tankmates. Provide enough food there for the fish. Remember, she will need plenty of energy reserve during the birth process. 

Here’s how to prepare your molly for birthing in detail. 

1. Create a Suitable Environment 

Creating a suitable environment should be any molly parent’s priority. For example, you should set up a separate breeding or nursery tank. This is where you will transfer the female to ensure she gets the much-needed space and peace to give birth. 

The conditions in the nursery tank should match those in the main tank. Remember you want your molly in good shape and not stressed. The ideal tank conditions you need to provide include; 

  • Temperature range: 75-82 degrees Fahrenheit
  • pH: 7-7.8 

In a nutshell, keep the right conditions to facilitate your fish’s health during its last phase of pregnancy. 

2. Isolate the Pregnant Molly

For the safety and peace of your fish and the fry that will be born, ensure you isolate the pregnant molly from the rest of the tankmates. 

Isolation or separation provides the pregnant individual with calm and enough time to rest and concentrate on the forthcoming delivery of fry. Consider the tank dimensions you are transferring the molly for birth. 

Ideally, provide a nursery tank with a 5-10 gallon capacity. This is enough for the young fry as they are still small. However, the tank size can vary depending on the number of expected fry. 

3. Create More Hiding Places

Remember to add hiding places in the tank as you prepare for your molly to give birth. These may include floating plants, stones, breeding traps, and artificial caves. 

With enough hiding areas, the fry can always evade their attackers, which include their mothers. 

4. Provide High-Quality Nutrition 

To ensure better health, consider feeding your pregnant molly a nutritious diet. For example, supply your pregnant fish with live or frozen foods like brine shrimp or daphnia to support the mother molly and the growing fry. 

However, you should not overfeed your fish. Overfeeding can lead to health problems such as bloating and constipation. In other instances, your fish may even die. 

How to Care for Molly Fry

Molly Fish Fry


You can care for molly fry by protecting the little fish from being preyed on by other adult fish or even their mother. Once they are born, remove the female Molly from the nursery tank and return it to the main tank. Fry may need a separate 10-gallon tank without their mother. 

In addition, ensure the following:

  • Proper filtration: Install a simple foam filter braced with an air pump. This ensures that fry will not be sucked up or get stuck in the filtration system. 
  • Add plants to the tank: Whether they’re live or artificial, have those placed in the tank to cover the little fry. 
  • Maintain proper temperatures: Preferably 72-84 degrees Fahrenheit (22.22-28.89 degrees Celsius) in the tank to keep the fish warm and active. 
  • Change water in the tank: It’s vital to keep changing the water at 20 per cent daily to remove impurities and maintain freshness.

Final Thoughts

If you’ve been wondering how long your molly fish will take to give birth, I hope this post has answered that.

A key to a successful molly fish delivery is taking good care of the fish by providing the necessary nutrients for the fish.

When it comes to taking care of your molly fish fry, ensure proper filtration and have plants in the tank. These plants provide a safe haven for fry to hide.

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