How Long Do Mollies Stay Pregnant?

Unlike other fish that lay eggs in clusters, mollies are known for delivering live fry. How long does that take, though?

This is a burning question lurking in many of molly owner’s minds.

Read this detailed guide on ‘How Long Are Mollies Pregnant For?’ and find all you need to know!

How Long Does Pregnancy Lasts For a Molly Fish?

A molly fish stays pregnant for up to 40 to 60 days. Their pregnancy’s duration, better referred to as the ‘gravid’ period, may vary based on several factors; however, 60 days is the average time.

The gestation duration for mollies varies from specie to specie. For instance, pregnancy in dalmatian mollies may last up to 70 days.

A molly fish can also store male sperm inside their bodies for several months. This way, they can fertilize the eggs later at different cycles.

The usual egg fertilization cycle for mollies begins every 30 days. Therefore, a molly can get pregnant repeatedly, without any significant time gaps in between.

When a molly is gravid, identifying the pregnancy can be a real challenge. It can take several days until mollies start showing signs of pregnancy.

So, how do you figure out if your molly fish is gravid or not? Let’s find out.

How To Identify Pregnancy In Molly Fish?

Identifying pregnancy in mollies can be challenging, but several factors can help.

If you are trying to determine whether your molly fish is pregnant or not, look for the following signs and behavioral changes:

Sign # 1 – You Will Notice Your Molly’s Belly Swelling Up

The first and foremost way to confirm pregnancy in mollies is to look for a swollen belly.

If you notice slight plumpness around the abdomen areas of your molly, chances are your molly may be pregnant.

As a molly’s belly can hold up to 100 babies at a time, their belly will be prominently rounder during pregnancy. The more fries inside a molly, the rounder the belly.

Especially when a molly is nearing the birthing period, the belly will appear extra round and firm.

Once you see this sign, you will have to make arrangements to make your pregnant molly feel comfortable.

Sign # 2 – You Will Notice a Gravid Mark Near The Belly Area

Confusing a chubby molly with a pregnant one is quite common. As mollies naturally have a rounder belly shape.

Therefore, you need to look for alternate signs, like a gravid mark.

A gravid mark appears in the form of a dark-colored, triangular-shaped mark that is usually found under the molly’s belly area or near the anal cavity.

This gravid mark is a sure-shot sign of a molly’s pregnancy, and you can easily detect it with naked eyes.

You have to use a bright UV light in your aquarium, and you can easily find the gravid spot.

The darkness in the gravid spot comes from the baby fry inside the molly’s belly. As the baby fry starts growing inside the body, the gravid mark becomes more prominent.

Sign # 3 – You Will Notice Your Molly Fish Is Acting Differently

A molly fish may exhibit behavioral changes when it is pregnant.

If you notice that your molly fish has suddenly started getting aggressive with the other tank inmates, there is a high chance that your molly is pregnant.

Note that your molly fish will only act out or get aggressive if it is being attacked.

They may also not attack in response and instead hide away in the corner of the tank to avoid further interaction.

When mollies get pregnant, they prefer staying alone and usually isolate themselves from the other fish in the tank.

It is encouraged to maintain hiding spots in the fish tank so mollies have their own personal space.

If you are looking for behavioral changes in your molly fish, the signs are most likely to appear after the first week of pregnancy.

Sign # 4 – Your Molly Will Have An Increased Appetite

Another common sign to look out for when identifying pregnant mollies is increased appetite. If your molly fish starts eating more food than usual, it could be pregnancy cravings.

Pregnant mollies tend to eat more food than usual as they need to store it for the fry inside them.

Sign # 5 – Your Molly Will Stay Close to Warmer Areas

Pregnant mollies seek comfort in warmth. So, if you notice your molly fish swimming close to the heater in the fish tank, this could be a sign of pregnancy.

Mollies like warmer temperatures when they are pregnant as this helps with the gestation period where they need to stay at a consistent temperature.

You may also notice your mollies swimming close to the water surface as the water is warmer on that side, with UV light warming up the surface.

So, whether near the heater or water surface, if your molly fish is constantly looking for warmer temperature water, there are high chances that it is pregnant.

Tips for Taking Care of Pregnant Mollies

To ensure your mollies are happy throughout their pregnancy period, you need to ensure a comfortable environment and ample food supply.

Here are a few valuable tips that can help make the pregnancy period easier for mollies:

Tip # 1 – Move Pregnant Mollies to a Separate Water Tank

While mollies are friendly and active in nature, they prefer being alone during pregnancy. This explains why some mollies become aggressive or isolated all of a sudden.

To help your pregnant mollies feel at ease, it is better to move them to a separate water tank. Ensure that the tank is spacious and has plenty of hiding spots for your mollies.

Keeping mollies in a separate tank will also help them feel safe and comfortable during the birthing time.

Tip # 2 – Create a Warmer Environment for Your Pregnant Mollies

As discussed earlier, pregnant mollies prefer staying near warmer areas to maintain consistent body temperatures.

For this purpose, you can create a cozy and warm environment for them.

Get a heater and maintain a water temperature between 20 to 30 degrees celsius to make your mollies feel at ease.

Tip # 3 – Feed a Nutrient-Rich Diet to Your Pregnant Mollies

When mollies are pregnant, they need to have a healthy amount of nutrient-rich food for energy. It is advised to feed more lipids and proteins to your pregnant mollies.

Mollies tend to eat more food during pregnancy as this helps fulfill the nutrient requirements needed for developing an embryo at the early stages.

A healthy mix of wet food and dry fish pellets makes the perfect diet for pregnant mollies.

Make sure that you regularly feed your mollies and increase the portion size, too, so they stay healthy throughout the pregnancy period.

Tip # 4 – Don’t Forget To Decorate The Tank

As mollies are naturally vibrant and active, they prefer a lively and colorful environment during pregnancy.

While you may already have kept your pregnant mollies in a separate tank, it is advised that you decorate the tank with plenty of plants and colorful decor items to make your mollies feel at home.

Make sure you also include several hiding spots for your mollies to stay there when they are close to giving birth.

Now that we are well-versed on how a molly’s pregnancy works let’s learn more about their birthing process.

How To Tell When Mollies Are About To Give Birth?

Mollies can hold up to hundred fry babies at a time, so the birthing time can be crucial.

Keep a look out for the following signs to ensure that your mollies give birth safely and comfortably.

Sign # 1 – The Gravid Spot Will Become More Prominent

When a molly fish is about to give birth, the gravid spot will become more prominent and will be clearly visible now.

You can find the spot under the belly or near the anal cavity, so look out for the sign and be prepared.

Sign # 2 – Your Molly Will Start Looking For Hiding Spots

Mollies prefer giving birth in isolation and peace.

Therefore, if you notice your molly fish hovering around hiding spots and seeking distance from other inmates, it means that they are about to give birth.

As mentioned earlier, it is better to keep mollies in a separate tank when they are about to give birth.

If that’s not possible, make sure you add plants, shells, and other items in the tank where mollies can give birth to their fry comfortably.

Sign # 3 – You Can Notice Babies’ Eyes Through The Belly

As mollies are about to give birth, their embryos grow in size so much that you can see the baby fry eyes through the belly.

When the fry eyes start to visibly show inside the belly, it is about time for mollies to give birth.

Sign # 4 – You Will Notice A Round Bump Under The Gills

Besides the gravid spot, you may also notice a round bump under the gills of your molly fish as the birthing day gets nearby.

This bump indicates that the womb is at its full capacity. The molly’s baby fry is ready to come out any given time after this bump becomes prominent.

The Bottom Line

We hope you enjoyed reading this guide on ‘How Long Are Mollies Pregnant For?’ and will refer to it the next time your molly fish is pregnant. 

Just make sure that you follow the tips on taking care of pregnant mollies to ensure your molly stays safe and healthy. Best of luck!

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