How to Tell If a Black Molly Fish Pregnant & (What to Do!)

How to tell if a molly is pregnant? If you’re an aquarist, you know how exciting it is to experience the miracle of life inside your tank. Watching a Black molly fish pregnant and releasing its eggs and fry into the water can be mesmerizing!

Plus, who wouldn’t want some more activity in their aquarium?

However, not all pregnancies are planned or triggered by the fish keeper – sometimes, we are surprised with new additions!

If you recently noticed your black molly fish giving birth to fry unpredictably, this post is for you!

black mollies fish

We’ll cover everything from identifying when your black molly is pregnant to best practices for caring for them during gestation and what to do after they have babies.

So read on if you want to learn more about black molly pregnancy, including signs of pregnancy and what steps need to be taken afterward.

With this knowledge in mind, any surprise litter will become manageable quickly!

Is My Black Molly Fish Pregnant?

How to tell if a black molly is pregnant? The first thing to determine when assessing your black mollies is whether or not they are pregnant.

This can be a tricky task, as the gestating process for this fish does not always produce obvious signs.

Male and female mollies reach sexual maturity at approximately 12 months, making them a quick and efficient source of aquatic life.

Did you know female mollies possess a unique biological process that allows them to produce offspring without the presence of a male?

A fascinating fact is that they can store sperm for up to several months and reliably reproduce every 30 days!

How to Identify Pregnant Black Molly Fish?

Are my black mollies pregnant? and what does a pregnant molly look like? The most reliable way to identify pregnant Black Molly Fish is to look for a blackish mark on the black molly gravid spot.

The gravid spot on black molly, is located just behind the dorsal fin, near the base of the tail, and should be more visible in female fish than male mollies.

This discoloration (usually dark brown or nearly black) indicates that eggs have developed in the ovaries and are ready to spawn.

In addition to this color change during pregnancy, other signs of potential spawning activity can include egg spots along their lateral line or an enlarged abdomen due to developing eggs.

Keep an eye out for these changes as they tend to occur before external physical black molly pregnant signs such as increased vent size become visible.

Black Molly Fish Pregnant Signs

What does a pregnant molly fish look like? Some of the most common indications that your female molly fish may be carrying eggs include the following:

  • Swollen Vent – the most easily identifiable sign is a swollen vent, which can appear a few days before the fish gives birth
  • Increased Appetite – pregnant mollies will often display an increase in appetite as they require more nutrients to sustain the developing eggs.
  • Darker Colors – some female mollies may become darker or duller in color as their pregnancy progresses.
  • Abdominal Droop – a pregnant molly’s abdomen may appear more rounded and prominent, but sometimes it will droop slightly as the eggs fill her body cavity.

What to Do If Molly Fish Is Pregnant?

Molly fish are popular aquarium pets, but what do you do if one of them becomes pregnant? 

If you’re like most people, you probably don’t have a lot of experience dealing with pregnant Molly fish. 

This video provides an overview of the steps you need to take if your Molly fish becomes pregnant. We’ll also discuss the importance of providing a suitable environment for the fry and how to care for them once they’re born.

How Long Are Black Mollies Pregnant?

How long is a black molly fish pregnant? Black Mollies are pregnant for an average of 60 days. This gestation period can vary from a few weeks to as long as three months of age, depending on the size and age of the female.

The fry (baby fish) must be manually separated from the adults when they are born, or their parents may eat them. 

The mother, Black Molly’s diet should consist of high-protein foods such as frozen or live brine shrimp, bloodworms, and tubifex worms during her pregnancy to ensure enough nutrition to support her and her brood.

She will also require more space to swim freely during this period; adding an extra tank is recommended. 

Once the fry is born, they should remain with their mother until they become independent swimmers at around three weeks old; 

afterward, it is best practice to safely transfer them into a separate tank with plenty of hiding spaces where they won’t get attacked by adult fish or sucked into filter intakes.

How Do Black Molly Fish Give Birth?

Pregnant black molly fish giving birth is known as “free-spawning,” meaning that the pregnant female molly will release her eggs into the water column, and the male molly will fertilize them.

Once the eggs are released, they sink to the bottom of the tank, where they attach themselves to surfaces with a sticky substance. After a few days, they hatch.

It is crucial to monitor the aquarium during this process so that you can separate the fry from the adult mollies and provide them with adequate care once they hatch. With proper care, your black molly fry should reach adulthood in about 8 to 12 weeks!

Black Molly Pregnancy Stages

Black mollies typically go through four stages of pregnancy. Here are the black molly pregnant stages:

1. Pre-Spawning Stage: In the pre-spawning stage, males and females will start to display courtship behaviors such as tail twitching and fin flaring. The female’s abdomen may appear slightly swollen due to eggs in her ovaries.

2. Egg Laying Stage: The female will lay her eggs on a flat surface, often in clumps or “strings.” Depending on how many eggs she produces, there can be anywhere from 2 to 500 strings per spawn!

3. Developmental Stage: Once the embryo has been fertilized, it begins developing into a fry. During this stage, the fry will feed off of the yolk sack inside the egg until they are ready to hatch.

4. Hatching Stage: Finally, after about two weeks of development, the eggs will begin to hatch, and tiny molly fry will start emerging from their shells!

At this point, separating them from their parents is essential, so they don’t get eaten.

Once all these black molly pregnancy stages have been completed, and the fry have been separated from their parents, you can sit back and enjoy watching your new fish grow!

What Does a Pregnant Black Molly Look Like?

What do pregnant molly fish look like? Pregnant molly fish behavior and appearance will vary depending on the species.

Common indicators of pregnancy include an increase in appetite, darker and duller body color, and a noticeable abdominal droop.

The female’s abdomen may appear more rounded or prominent as the eggs fill her body cavity.

pregnant black molly fish

Additionally, it’s important to provide plenty of hiding spots for the female, as she will be more skittish during this time.

Please note that these behaviors and appearances may vary depending on the species of Molly fish you have in your aquarium.

If you are unsure if your molly is pregnant, it is best to consult a veterinarian or an experienced aquarist for confirmation.

When to Separate Pregnant Molly?

When separating pregnant molly from their tank mates, the ideal time to do this is as soon as you notice signs of pregnancy.

Some common signs include increased size, a curved belly shape, and darkened patches on the belly, which indicate eggs.

If your molly shows any of these symptoms, it’s best to separate them immediately.

This will prevent other fish from eating their young or causing injury due to aggressive behavior during spawning.

Remember that as soon as your female molly gives birth, it should be returned to its original environment with plenty of hiding places and plants for cover so the fry can survive.

How Many Babies Do Black Mollies Have?

Black mollies typically have between 40 and 100 fries per spawn. Depending on the size of the female, she can lay anywhere from 10 to 50 eggs per batch.

However, it’s important to note that not all eggs will be fertilized and hatched; some may become damaged or eaten by other fish in the tank.

Moreover, the number of fry can also vary depending on environmental factors such as water conditions and pH levels.

Taking Care of Black Molly Fry: (Black Molly Fish Babies Care)

Once the eggs have hatched, you will need to provide adequate care for the fry if you want them to survive and reach adulthood.

Fry should be kept in a separate tank from their parents, as they are vulnerable to attacks from adult fish. The fry tank should have plenty of hiding spaces and structures for them to hide in, like plants, driftwood, and caves.

The aquarium should also be well-aerated to ensure proper oxygen levels and heated to a temperature between 75°F and 82°F. You should also Feed Baby Molly Fish with high-quality food such as Baby Brine Shrimp or specially formulated fry flake foods to ensure proper nutrition and growth.

Lastly, you should perform regular water changes to keep the tank clean and monitor water parameters regularly to ensure they are within safe levels for your fish.

Why Does My Black Molly Have White Spots?

Black Molly pregnant white spot can be caused by various factors, the most common being parasites or Ich. If you notice white spots on your black molly fish, it is best to take them to a veterinarian for treatment as soon as possible.

Sometimes, these spots may also be caused by stress or poor water quality. Monitor your aquarium closely and keep up with regular water changes to ensure your fish are healthy.

With proper care and attention, you should be able to get rid of the white spots on your black molly in no time!


So, how to tell if a black molly is pregnant? If you think your black molly is pregnant, the first step is to confirm whether or not she is carrying eggs. You can do this by gently pressing her abdomen; if you see small black spots, she is indeed Black molly fish pregnant. Once you have confirmed that your fish is expecting, there are several things you need to do to ensure a healthy black molly pregnancy and delivery. First, increase the amount of aeration in the water and the frequency of partial water changes.

Second, provide plenty of live plants for your fish to hide in; pregnant black molly fish tend to be very skittish. Finally, give her plenty of high-quality flake food rich in vitamins and minerals – Hikari Bio-Pure Freeze Dried Bloodworms are an excellent option. With some care and attention, your Black Molly Fish will have a healthy pregnancy and deliver beautiful baby fry!

Now that you know all about Black Molly Fish, you can successfully molly fish breed and raise your tiny fry. You’ve made it to the end of your black molly fish journey!

Congratulations – you are now a proud owner of some beautiful fish fry. We hope this guide has provided you with all the information you need to care for your fish and ensure a successful mollies breeding journey.

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About Me

I am the founder of, a devoted wife and mother, and an avid fish enthusiast. My aim is to assist fellow fish lovers worldwide in understanding how to properly care for and breed their pet fish.

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