How To Tell if My Molly Fish is Pregnant?

By Nadine Oraby | 2020 Update

It is hard to tell when a fish is pregnant. You can’t just take one look at the bulging belly and confirm whether your fish is pregnant or not.

In the same way, it can be difficult to tell whether your molly fish is pregnant or not because of its small size. A behavioral change, such as isolation, is a dead giveaway that your molly fish is pregnant.

 A molly fish’s pregnancy is fascinating as it can give birth up to 50-80 fry at a time.

So, how do you know when your molly fish is pregnant? There are several ways to figure that out.

Signs That Your Molly Fish is Pregnant

Many ways can help you discover your molly fish’s pregnancy. The most noticeable symptoms, such as:

  • A swollen belly: If you have doubts that your molly fish is about to give birth, then keep an eye on its stomach. You can take pictures to notice any difference is the size of its belly as molly fish is tiny in format.
  • Mood Swings: Yes, you read that right. If you notice your molly fish, which is usually very excited and full of life trying to find a safe and alone space in the tank, then that means it is pregnant.
  • Defensive Nature: You may note that your molly fish has occupied a particular space and refuses to come out from there. Every other fish in the tank will not try to approach it, so keep an eye out for that sort of behavior.
  • Change in Color: According to Wikipedia, when a guppy is pregnant, it shows a discoloration on the part where its tail begins, and the color darkens within time. It is a visible sign of pregnancy in molly fish.
  • Visible Fry: In case you have missed the first few days of pregnancy, you can squint your eyes and see the fry growing in your molly fish’s belly

Now that you know that your molly fish is pregnant, what is next?

What are the steps that you can take to ensure that the fry is safe and healthy? What should you feed it and how much?

There are so many queries that will arise, and you will be concerned for the fry and rightly so.

What To Do If Your Molly Fish Is Pregnant?

Keep in mind that molly fish can give birth to 50 fry in one go, and you definitely won’t have enough space to keep all of them.

So, what can you do once you have figured out that your molly fish is pregnant?

For starters, you can decide whether you want to keep the fry or not.  It will make things less complicated.

If you don’t have the time to take care of babies, then you can set up another tank and keep your pregnant molly fish there.

This way, when your molly fish gives birth to the fry and the fry are big enough. You can either give them to your friends or donate them to places where they will be safe.

On the other hand, if you do wish to keep the fry and care for them, then you will have to make some arrangements.

Such as:

  • Buying two tanks; one for the fry and the other for the mother before she joins other fish
  • Feed your molly fish at least thrice a day to keep her healthy
  • Once you know the gender of the fry, try to keep them separate as they will start breeding at that stage
  • Keep enough feed for the fry, as they are just babies they will need at least four feeds a day
  • A study reveals that it is advisable to feed the fry a mixture of dry and fresh food

How to Setup a Tank For A Pregnant Molly Fish (video)

The Life Cycle Of A Molly Fish Pregnancy

A molly fish gets pregnant and gives birth after 60 days. The number of days can vary because of water temperature, type of molly fish, and other factors.

However, you should be extremely careful and monitor your molly fish’s pregnancy so that it can deliver healthy fry.

First, it’s necessary to understand how the pregnancy of a molly fish progresses within time

The life cycle of the molly fish’s pregnancy can be understood as follows:

  • A molly fish will get pregnant by internal fertilization; this means that the male sperm meets the female egg inside the female’s body during sexual reproduction
  • Next, you will start noticing signs mentioned in the article above that your molly fish is pregnant
  • Your molly fish will then give birth to fry after a few weeks. You can either buy a breeder’s box or separate your molly fish’s tank
  • As soon as your molly fish gives birth to all the fry, place her in a different container away from the babies because yes she will try to eat her children
  • The last step would be to separate the fry after a few weeks to avoid breeding. You can quickly identify the gender by looking at the fins of the molly fish. The fins of a male molly fish are slightly larger.

How Many Fry Can A Molly Fish Birth? (video)

It sounds absurd when I tell you that a molly fish can give live birth to 100 babies at a time, but it’s the truth.

Don’t believe me? Take a look at this video and see for yourself.

A pregnant molly fish is nature’s wonder at its finest.

Pregnant Molly Fish Behavior with Other Fish

When a molly fish is pregnant, she isolates herself from other fish present in the tank.

But, what happens when other fish try to approach a pregnant molly fish? Do the other fish know that the molly fish is pregnant?

Does the male molly stop interact with the female molly once it finds out about the pregnancy?

Read below to find out more.

  • You may notice that your pregnant molly fish is cold and distant towards male molly and that is completely fine
  • The pregnant molly may also show signs of aggression towards other fish present in the tank as they have an overprotective nature and tend to look out for themselves
  • They will try to be with another female molly present in the tank as it gives them a sense of brotherhood

When your pregnant molly starts isolating herself to the extent of not leaving a particular place, then you should put her in a separate tank so that it can give birth comfortably.

Types Of Molly Fish And Their Characteristics

When I say “molly fish,” your molly fish that is present in your tank right now will come to your mind.

But, molly fish are of different sizes, colors, and shapes, yet they exhibit similar characteristics.

Some of them include:

  • Dalmatian Molly Fish: Dalmatian Molly fish exhibits beautiful patterns, hence the name “Dalmatian.” They are about 5 inches in size and live peacefully.
  • Black Molly Fish: A black molly fish is the most popular molly fish present. They love to eat and require significant space in the tank.
  • Gold Dust Molly Fish: The Gold Dust Molly fish is magnificent because of the golden specks on its deep black skin. They love water-based plants.
  • White Molly Fish: The white molly fish also grows up to 5 inches in size. The only difference is that a white female molly fish will look big and bulky than the white male molly, which will have orange markings.

Although there are other types of molly fish as well, these were just some of the common ones you’d find in any aquarium.


Other Related Questions

Is it true that molly fish eat their babies?

Nature is beautiful, but scary.

As much as I hate to admit this, it is true that molly fishes their fry after giving birth to them. 

Is it true that the black molly fish tends to be more aggressive when compared to another type of molly fish?

No, Molly fish by nature are not aggressive. The black molly fish is not aggressive, but it is considered aggressive because of its large size.

When should I separate the female and male fry that my molly fish gave birth?

As soon as you start identifying the male molly and female molly, it would help if you separated them or else they will begin to breeding, which can cause chaos in the tank.

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