The 5 Main Signs of a Pregnant Molly About to Give Birth

Mollies give birth to between 40 and 100 fries. Such a large number of fries comes at a cost; you must take good care of your pregnant molly fish. Therefore, if you know the signs of a pregnant molly about to give birth, you can take the necessary steps to ensure that both the molly fish and her fry survive and thrive.

A pregnant molly about to give birth displays physical signs like the development of an opaque gravid spot and a square bulging stomach. It also displays behavioral signs like aggressive tendencies, loss of appetite, isolation, and abnormal swimming patterns. These are the crucial signs to prepare you for D-day at the end of your molly’s gestation period.

In the rest of this article, I’ll discuss the physical and behavioral signs of a pregnant molly about to give birth. You’ll also learn how to care for a molly fish about to give birth. Keep reading!

2 Main Physical Signs of a Pregnant Molly About to Give Birth

The gestation period for a molly fish lasts approximately 60 days. Molly fish giving birth is a challenging moment that requires your attention for the following reasons:

  • To provide a conducive environment for the fish to give birth.
  • To protect the fries from predators and other dangers.
  • To keep an eye on the fish and assist whenever necessary.

You must know the physical signs that your mollyfish is about to give birth to provide the above necessities. 

Being aware of How to know your Molly fish is about to give birth will allow you to take optimal care of your fish.

To help you with that we have compiled a list of molly fish giving birth signs;

1. The Development of an Opaque Gravid Spot

Molly Fish Gravid Spot

The formation of an opaque gravid spot as shown above on the fish’s abdomen is a key sign of a molly about to give birth.

However, most people presume that an opaque gravid spot on a molly’s abdomen indicates that the fish has eaten too much. This assumption is incorrect, as the gravid spot appears long before birth. Furthermore, the gravid spot disappears after the fish gives birth.

When your molly fish is pregnant and about to give birth, the gravid spot appears as a dark area surrounded by small white dots that becomes increasingly translucent as the molly nears its due date. Eventually, the area becomes opaque towards the end of molly fish’s pregnancy cycle.

The opaque region is a cluster of fries about to be born. You can confirm the presence of these fries using your fish tank’s UV light. The light will illuminate the cluster, helping you to confirm your molly’s fries.

Find Out: Signs of a Stressed Pleco

2. A Square Bulging Stomach

pregnant molly about to give birth
Molly with a squared bulging belly

Like any other organism, pregnant mollies will develop swollen stomachs. However, a swollen belly does not always indicate that a pregnant molly fish is about to give birth.

The shape of the swollen stomach is an efficient confirmation that your molly fish has reached the end of its gestation period.

When the fish nears its due date, the stomach becomes distended, taking on a square outline that resembles a box. This makes it easier to differentiate between a bloated stomach and one preparing to give birth.

3. Behavioral Signs of a Pregnant Molly About to Give Birth

Although the aforementioned physical features are the main signs of a pregnant molly about to give birth, the behavioural signs are equally important in helping you prepare for this moment.

Here are the behavioural signs that your molly fish is about to give birth:

1. Aggressive Tendencies

If you notice a sudden change in your molly’s behaviour, it could be indicative of impending birth. Pregnant mollies often become aggressive and chase other fishes away from their territory or food sources. This aggression during the gestation period for molly fish lasts from a few days to weeks before delivery.

If you have stacked the aquarium with large fish, the pregnant molly tends to push others away to create more space for its offspings.

Due to the aggressive tendencies of mollies about to give birth, it’s advisable to separate the pregnant molly. Separating a pregnant molly about to give birth is vital if you want to keep most of the fish alive.

2. Loss of Appetite

Pregnant fish will have a high appetite to get sufficient food for the fries. However, as the fish nears its due date, the appetite begins to decline in anticipation of giving birth. If your pregnant molly loses its appetite, it means she’s about to give birth.

A common behaviour to note is that the fish may lose appetite for specific foods and not others. Such behaviour is attributed to a preference for certain foods that impacts the fry’s development.

If your pregnant molly starts losing its appetite, it’s important to provide a variety of foods to help satisfy the fish and support the fries’ growth. You should also avoid overfeeding when your molly is about to give birth because excess food may result in low fry survival rates.

3. Isolation and Erratic Swimming Patterns

Female mollies that are about to give birth tend to isolate themselves. The fish will be looking for a safe place where it thinks the fries can stay.

Although isolation in most fish is attributed to stressful housing conditions, this is a different case. Giving birth in mollies is induced by hormones that make the fish unsettled when interacting with others.

If you don’t provide hiding spots in the aquarium for your pregnant molly, she will be more stressed, which can lead to withdrawal symptoms, affecting the delivery process.

You can install the following hiding spots for your pregnant molly: 

  • Aquarium plants: Plants like java moss, java fern, and oriental water fern provides good hiding spots that will make your pregnant molly comfortable.
  • Aquarium rocks: This is your go-to option if you want a more natural feel in your aquarium. These rocks provide sufficient fissures for your tank mates, meaning your molly will have a place to run to when she wants to isolate herself from the other fish.
  • Aquarium ornaments: Ornaments are known for creating crevices where the fish can take refuge. Therefore, you can rest assured that the fish will have a place to run to when she wants to be alone. Pipe ornament is an excellent option that’s fun and provides sufficient shelter that prevents stress. The hollow design of this ornament is also vital for a pregnant molly about to give birth, as it will isolate the fries from the rest of the fish. 
  • Driftwood: This is an option that creates an enticing aquascape. Driftwood has crevices and caves that saves as hiding spots for most fish.

Isolation is often accompanied by erratic swimming patterns in pregnant mollies. 

Besides swimming slowly, you may notice that the fish stays in one spot, not swimming. This is a normal occurrence since birth hormones make the fish less active. 

You may see the fish shivering, especially the tail, when you observe it closely. The shivering is attributed to the labour pains the fish experiences at this moment. As this is normal, it’s your responsibility to help the fish through this period. Besides food, you should ensure the tank has conducive conditions for the fish and is free of ammonia. 

Is It Necessary to Move a Pregnant Molly to a Separate Tank?

It’s necessary to move a pregnant molly to a separate tank if you want to breed her. Moving a pregnant molly to a separate tank ensures that the fries are safe from other fish and the mother.

Molly fries are always tiny, making them easier to be eaten by their mother or other fish in the man tank. Therefore, if you aim to breed your molly for more fish, consider moving her to a separate tank when she nears the delivery date. 

It’s advisable to go for a tank between 5 and 20 gallons when separating a pregnant molly. The focus is to ensure the fish has sufficient space to move around during the delivery. 

The separation tank must also contain multiple broods if you intend to keep the mother molly with her fries. However, having a separate nursery tank for the fries is a good idea. This ensures that the fries are safe even from their mother.

Here are essential considerations for setting up a nursery tank for your molly fries:

  • Tank size: Mollies give birth to many fries that will need sufficient space. A 10-gallon nursery tank is enough if you want to seclude the fries from their mother until when they come of size.
  • Tank filtration: Filtration is essential for fries since they are susceptible to debris, toxic ammonia, and nitrites. You should set up a foam filter based on the tank’s size.
  • Incorporate aquarium plants: The nursery tank should have aquarium plants to cover the fries. The plants also act as a breeding trap for your molly. You can choose artificial or live plants, mixing broad and narrow-leafed options. 
  • Tank temperature: The fries will only survive if you provide an optimum tank temperature. The temperature shouldn’t be too hot or too cold. Molly fries need water temperatures between 23 and 28°C (72 and 84°F). You should monitor the tank’s temperature using a thermometer to ensure consistency. 

Expert Tip: You should feed the fries after introducing them into the nursery tank. You should grind adult molly fish to reduce the flakes before feeding them to the fries. It’s also worth noting that the adult molly shouldn’t be kept in the same tank with the fries as she can eat them. You can only transfer the fries into the main tank after at least 2 weeks as they will be large enough that other fish can’t eat them.

You can leave the pregnant molly fish in the main tank with other tank mates if you don’t want to breed her. In this case, the other fish in the tank will eat most of the fries. It may be surprising that the mother molly will also take part in consuming her fries.

How to Take Care of a Pregnant Molly Fish

One of the requirements for a safer and healthy delivery in human beings is proper care. The same applies to a pregnant molly fish.

Caring for a pregnant molly fish aims to eradicate stress and ensure she gets the right nutrients for her health and fries. This is especially important if you want to breed her.

The following are some of the ways to take care of a pregnant molly fish: 

  • Give her foods with the necessary nutrients: Pregnant mollies need sufficient omega-3 fatty acids for the development of the fries. Therefore, you should give her foods like shrimp, pollock, anchovies, and herring.
  • Provide good hiding spots: Pregnant mollies always look for isolation spots to prevent stress. Therefore, you should ensure that the tank has good aquarium plants and rocks for the fish to hide as she pleases.
  • Provide optimum tank conditions: Besides pregnancy, poor water conditions are other stressors for pregnant mollies. You should ensure the water is filtered continuously and has temperatures between 23 and 28°C. 

Final Thoughts

A pregnant molly about to give birth will display signs to help you take the necessary actions. These signs should help you put in place mechanisms to prevent the fish from eating her fries.

You should transfer the pregnant molly about to give birth to another tank if you want to breed her. This is to prevent the other fish from eating the fries.

Finally, you should return the mother molly to the main tank and keep the fries in a nursery tank for at least two weeks. 

Frequently Asked Questions

What is the gestation period for molly fish?

The gestation period for mollies is about 60 days, after which the fish will be mature and ready for birth. When the due date comes, you should ensure the molly has birth traps to facilitate the process.

Do mollies poop before giving birth?

Mollies poop a lot before giving birth to extract the extra waste not needed in the body before childbirth. Removing this waste makes it easier for the fish to give birth. Therefore, when you notice your pregnant molly pooping more than usual, you start preparing for fries.

How Long Are Molly Fish in Labor For?

Molly fish are in labor between 1 and 24 hours. It’s advisable to be extra careful during this time to prevent the fry from being eaten by their mothers or other fish in the aquarium.

How to know if a molly fish is about to give birth?

Towards the end of its gestation period, your molly fish will have a highly squared-off belly, to the point where you would believe it will burst, just before she is ready to give birth.

 It is a strong sign that the molly will soon give birth, maybe within the next seven to ten days.

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