Pregnant Mollies (Everything You Need Know - Identification to Care)

Pregnant Mollies (Everything You Need Know – Identification to Care)

Pregnant molly

It’s vital to recognize the early signs of pregnancy in mollies to provide the necessary care.

This guide will help you spot the signs of pregnancy in mollies and show you how to take care of them.

How to Identify Pregnant Mollies?

There are certain physical and behavioral changes that female mollies undergo while they are pregnant.

Given below are the signs that indicate your female molly is pregnant.

1. Gravid Spot

A gravid spot is a black spot on the abdomen near the anal vent of the fish. It’s a clear sign that your female molly is pregnant.

As the pregnancy progresses, this spot becomes dark and more visible.

The dark mark is actually the cluster of fry growing inside the fish’s body.

As the fry grow, the spot becomes more prominent, and the eyes of the fry are clearly visible.

The gravid spot is easily visible on colorful and light-colored mollies.

However, it’s difficult to identify it on black mollies due to their dark coloration.

2. Swollen Belly

A swollen belly is the most apparent indication that the female molly is pregnant. Normal female mollies have round bellies.

When a female molly becomes pregnant, the shape of her belly changes, it becomes thicker and more squarer.

Pregnant mollies look more plumb and chubby around the abdomen area.

3. Increased Appetite

An increase in appetite is another indication that your female molly is pregnant.

Pregnant mollies need more nutrition to nurture the fry developing inside them.

You may notice your female molly being more active during feeding, and she may even compete for food.

You must feed your pregnant molly a well-balanced nutritious diet for a healthy and safe pregnancy.

4. Behavioral Changes

Besides the physical changes, certain behavioral changes also indicate that your female molly is pregnant.

Aggression and isolation are the most common behavioral trait of pregnant mollies.

Pregnancy makes them overprotective of themselves so that they can stay safe.

You may notice your pregnant molly hiding more than usual.

A pregnant molly feels more secure when she is alone and away from her tankmates.

Sometimes, you may also notice your pregnant molly displaying aggression.

It will usually happen when she gets constantly chased and harassed by male mollies or other tankmates.

5. Need for Warmth

Pregnant mollies prefer to stay warm. So you may see them hovering near the heater or temperature stabilizer to seek warmth.

Pregnant mollies may also swim close to the tank’s surface area, especially if you have installed an overhead UV light source.

The heat emitted by the light source provides comfort to pregnant mollies.

How Long Do Mollies Stay Pregnant?

Mollies take around 35 to 45 days to give birth.

They can store the sperm inside their bodies for months after a single mating. Female mollies fertilize the eggs every 30 days.

This means they can get pregnant every month over a longer duration, even in the absence of a male molly.

The gestation period of mollies can vary depending on the species.

For example, the gestation period of dalmatian mollies can be up to 70 days.

The gestation period also depends on the environment and diet provided to the pregnant molly.

Mollies need a warm, stress-free environment to ensure a safe and healthy pregnancy.

5 Stages of Pregnancy in Mollies

Mollies are viviparous, meaning they give birth to live fry. They don’t lay eggs.

Pregnant mollies undergo various stages of pregnancy.

Identifying these stages is crucial to provide the best care to the pregnant molly and her fry.

Given below are the pregnancy stages of mollies.

1. Conception

Conception is the first stage of pregnancy in mollies. It usually occurs when you have a male and female molly in the same tank.

Conception is relatively easy as female mollies can retain the sperm from a single mating and use them to fertilize their eggs every month.

2. Embryo Formation

After fertilization, the eggs begin to form embryos. This usually happens 7 days after conception.

You can identify the embryos by their small size and dark color.

Also, the gravid spot becomes more visible during this stage.

3. Fry Development

As the pregnancy progresses, fry develop inside the female molly’s body.

During this stage, the female molly’s abdomen enlarges. The fry develop and reach maturity before they are ready for birth.

4. Pre-Birth

Pregnant molly in water

It’s the stage when the gestation period is over, and the fry are almost ready to come out.

If you look closely, you can spot the eyes of the young fish within their mother’s belly.

Also, the female molly will start to look for a safe place to give birth.

5. Birth

During this stage, the female molly will give birth to her fry.

The fry are born in batches; it can take a few minutes to several hours for them to come out.

After birth, the fry will swim away from their mother and start exploring their new environment.

How to Take Care of Pregnant Mollies?

Given below are some tips to ensure that your pregnant mollies have a safe and healthy pregnancy.

1. Separate the Pregnant Molly

Pregnant mollies prefer to hide most of the time to feel secure.

They usually lack the strength to fend off attackers. So they can easily get bullied or harassed by their tankmates.

Hence, separating the pregnant molly is a good idea to give her a safe and secure environment.

You can keep your pregnant molly in a separate tank away from the aggressive tankmates.

2. Provide a Warm Environment

Pregnant mollies prefer a warm environment. They actively look out for a heat source to regulate their body temperature.

The ideal water temperature for a pregnant molly is between 72°F to 78°F (22.2°C to 25.5°C).

So you can increase the water temperature by 2 to 3 degrees to make them feel comfortable.

3. Have Ample Hiding Places

Pregnant mollies prefer to hide from their tankmates while pregnant. They hide to avoid danger and harassment from other fish.

So, providing them ample hiding places to rest and feel secure is vital.

You can add plants, rocks, caves, and other decorations to create hideouts in the tank.

Mollies also like dark places to give birth. Hiding places allow pregnant mollies to give birth peacefully.

4. Feed a Nutritious Diet

Pregnant mollies need more nutrition than usual for a safe and healthy pregnancy.

A nutritious diet is also vital for the healthy development of their fry.

You can feed pregnant mollies a mix of flakes and high-quality live and frozen food like bloodworms, brine shrimp, daphnia, etc.

These foods are rich in proteins and other essential nutrients.

So they should be part of the daily diet of your pregnant mollies to meet their dietary requirements.

However, don’t overfeed your mollies since it can lead to health issues.

5. Create a Stress-Free Environment

Providing a stress-free environment goes a long way in ensuring a smooth pregnancy for mollies.

This includes good water quality, favorable water parameters, adequate living space, compatible tankmates, a nutritious diet, and regular tank maintenance.

You should also provide ample hiding places, proper water circulation and filtration, and a peaceful environment.

Signs that Indicate a Pregnant Molly Fish Is Ready to Give Birth

Given below are certain physical and behavioral changes that mollies undergo while they are close to giving birth:

  • The gravid spot under the belly will become darker and more visible.
  • In addition to a rounded abdomen, mollies will also develop a round area under the gills. This indicates that the womb has reached its maximum capacity. The pregnant molly will have the urge to give birth quickly to reduce the burden on her body.
  • As the embryos mature, you can notice their eyes and identify each fry. It’s a sign that the fry are fully developed.
  • Pregnant mollies lose their appetite when they are about to give birth. So you may notice your pregnant molly not swimming toward the surface when food is offered.
  • They usually prefer to hide more when they are close to giving birth.
  • Female mollies will start looking for a safe place to give birth.
  • Sometimes, the pregnant mollies can even become aggressive toward other fish in the tank.
  • The pregnant molly may shiver and breathe heavily. She may even shake her tail when ready to give birth. This is due to the stress associated with giving birth.

If you notice these signs, leaving your pregnant molly alone is a better idea to let her give birth in peace.

It’s also equally essential to provide a safe environment so that your molly can give birth without complications.


Mollies stay pregnant for about 45 days. Some signs to identify their pregnancy are a gravid spot, swollen belly, increased appetite, and behavioral changes. You can take care of a pregnant molly by keeping her in a separate tank, feeding her a nutritious diet, and providing her with a stress-free environment.

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