Do Mollies Eat Their Babies? Tips to Protect Molly Fry

When it comes to breeding fish, a common question that arises is whether mollies eat their babies. For many aquarium owners, ensuring the survival of their newborn mollies is crucial. However, this can be a tricky feat given that mollies have been known to consume their young.

Understanding the reasons why mollies eat their offspring can help prevent such incidents from occurring. This article aims to provide insights into the behavior of mollies and how aquarists can mitigate the risks of losing their baby mollies to their parents.

Overview of Molly Fish

Mollies are freshwater fish that belong to the Poeciliidae family. They are known for their vibrant colors and lively nature, which makes them a popular choice for aquarium enthusiasts. Mollies are also known to be prolific breeders and are capable of reproducing quickly.

Mollies are omnivorous animals that feed on a wide range of food, including algae, small insects, worms, and plant matter. However, their diet may vary depending on their environment and the availability of food.

In their natural habitat, mollies can be found in rivers, streams, and estuaries that have plenty of plants and other aquatic life. They prefer shallow, warm waters with a pH between 7 and 8.5.

Mollies are social animals and prefer to live in groups. They are relatively easy to care for and are a great addition to any aquarium. However, it is essential to provide them with the appropriate environment and diet to ensure their well-being.

Mollies are known to be excellent parents and will protect their offspring from predators. However, there have been reports of mollies eating their young. This behavior is often observed in overcrowded or stressful environments, where the parents may feel overwhelmed and lack the resources to care for all of their offspring adequately.

Mating and Reproduction In Mollies

Mollies are known for being prolific breeders and can produce numerous offspring during a single mating session. Typically, mating occurs when a male molly chases and nips at the female’s fins until she allows him to mate. Following successful copulation, the female molly can store the male’s sperm and fertilize her eggs over a period of time.

The reproductive cycle of mollies is relatively easy to understand. Female mollies can carry their fertilized eggs in their bodies, but if conditions are not suitable, they will release the eggs. After the female molly releases the eggs, a male molly will fertilize them, and they will hatch in 24-36 hours.

Mollies can produce several broods of fry – young fish – within a few weeks. In a single brood, a female molly can produce up to 100-150 offspring, depending on the species. These fry can grow quickly and reach full size in as little as six months.

It is common for molly mothers to eat their young, especially if they feel stressed, threatened, or the environment is not conducive to their growth. Thus, it is best to separate the adult mollies from their fry once the latter is born to ensure their survival until they are strong enough to survive on their own.

Breeding mollies is relatively easy, and they can produce a vast number of young. However, giving them proper care is crucial in ensuring that the fry survive and grow into healthy adult fish.


Why Mollies Eat Their Young

Mollies are fascinating creatures that can be found in freshwater aquariums around the world. However, many aquarium enthusiasts wonder why mollies seem to eat their babies. There are several reasons why mollies might eat their young, including:

  • Stress: Pregnant mollies can become stressed if their environment is not ideal. This can lead to the mother eating her young as a result of stress.
  • Lack of Space: Mollies that are kept in cramped spaces might eat their young as a way to control the population in their environment.
  • Lack of Food: If your mollies are not well-fed, they may eat their young as a way to preserve resources.
  • Nature: In the wild, the survival rate for molly fry is incredibly low. As a result, female mollies may eat their young as a way to ensure the survival of the strongest offspring.

Understanding why mollies eat their young can help aquarium enthusiasts create a more suitable environment for their pets. By ensuring that the water in the aquarium is clean and that the mollies have adequate space, stress levels can be reduced and the need for cannibalism can be minimized.

The Role Of The Environment in Fry Survival

The environment plays a crucial role in determining whether mollies will eat their babies or not. Here are some factors that can influence this behavior:

  • Water quality: If the water quality of the aquarium is poor, it can stress out the mollies and make them more likely to eat their babies.
  • Tank size: If the tank is too small, it can cause overcrowding and stress, which again leads to cannibalism.
  • Hiding places: Mollies need plenty of hiding places to keep their babies safe from other fish. If there are not enough hiding places, the babies are at higher risk of being eaten.
  • Food supply: If the mollies are not getting enough food, they may turn to eating their babies as a source of nutrition.
  • Predators: If there are other predators in the tank, such as larger fish or snails, mollies may feel threatened and resort to eating their babies as a way to protect them from harm.

As you can see, the environment is a crucial factor in mollies’ behavior towards their offspring. Therefore, it is important to provide a suitable environment for mollies to breed and raise their babies without danger or stress.


Ways To Prevent Mollies From Eating Their Young

Mollies are known for their tendency to eat their babies, which can be quite frustrating for pet owners. However, there are ways to prevent this behavior and ensure the survival of your mollie fry.


One simple solution is to separate the mollie fry from the adult mollies. This can be done by using a breeding net or a separate tank. It is important to make sure that the young mollies have enough space to swim and that they are not overcrowded.

Live Plants

Adding live plants to the tank can provide hiding places for the mollie fry. This can help protect them from being eaten by adult mollies. Live plants also provide a natural environment for mollies.


Feeding the adult mollies a high-quality diet can reduce their tendency to eat their young. Providing plenty of food for the adult mollies can also reduce the need for them to eat their young for nourishment.

Fry Food

Providing fry food specifically designed for mollies can ensure that the young mollies receive the proper nutrition they need. This can also reduce the chances of adult mollies eating their young.

Keep The Tank Clean

Keeping the tank clean and providing proper filtration can help reduce stress in the mollies. This can also reduce the chances of adult mollies eating their young due to stress.


Observing the behavior of adult mollies and their interaction with the young mollies can allow for early intervention if eating behavior is observed. This can help ensure the survival of the young mollies.

Overall, preventing mollies from eating their young requires proper care and attention. Using the above methods can help ensure that your mollies are happy and healthy, and that their young have the best chances of survival.


Do All Mollies Eat Their Babies?

Many people wonder if Mollies eat their babies when they breed. The answer is not straightforward, and it depends on various factors, such as the environment, the breed, and the individual fish’s behavior. Here are some considerations about Mollies and their offspring:

  • Some Mollies may eat their babies, particularly in stressful situations. Overcrowding, poor water quality, or lack of hiding places for the fry can trigger this behavior. A stressed or hungry Molly may see her own fry as an easy source of protein.
  • However, not all Mollies are cannibalistic. Some breeds, such as balloon Mollies, are more likely to avoid eating their fry. Also, individual Mollies may have different temperaments.
  • Providing an adequate breeding tank for your Mollies can reduce the risk of infanticide. A 10-gallon tank with a heater, a filter, and plenty of plants or decorations can offer a safe haven for the fry to hide and grow. Separating the pregnant Molly from other fish can also prevent stress and aggression.
  • Another way to protect the babies is to feed the adult Mollies well. If the mother and father have enough food, they may be less tempted to eat their young. Providing protein-rich foods, such as blood worms or brine shrimp, can also satisfy their nutritional needs.
  • Some aquarists suggest using breeding traps or nets to isolate the newborn fry from the parents. While this method may prevent cannibalism, it may also stress the babies and hinder their growth. Plus, it does not allow for natural behaviors and interactions.
  • If you observe a Molly eating her babies, resist the urge to intervene immediately. Sometimes, the mother may only consume dead or sickly fry to prevent disease or predation. Removing all the fry from the tank can also disrupt the biological balance and leave the parents stressed or confused. However, if the behavior persists and endangers the survival of the other offspring, consider separating the Molly from her young or rehoming her.

Finally, remember that Mollies are livebearers, which means they give birth to live fry instead of laying eggs. Therefore, their parenting style may differ from egg-laying fish. While cannibalism may seem gruesome to us, it is a natural behavior that has helped Mollies survive in the wild.

By understanding their needs and behaviors, we can provide the best care for our aquatic companions.

How To Care For Baby Mollies

Taking care of baby mollies requires patience and attention to detail. Here are a few tips on how to ensure your baby mollies stay healthy and thrive:

  • Separate the babies from the adults: Baby mollies are vulnerable to being eaten by the adult mollies, so it’s essential to keep them separated in a separate tank or breeding box.
  • Provide a suitable environment: Baby mollies need clean water, sufficient oxygen, and a temperature of around 78°F to grow and develop healthily. Keep the tank clean, change the water frequently, and ensure adequate filtration.
  • Feed them a balanced diet: Baby mollies need a varied diet to support their growth and development. Feed them finely crushed flakes, micro-worms, and brine shrimp several times a day in small portions. Avoid overfeeding, as it can lead to poor water quality and disease.
  • Monitor their health: Watch out for any signs of illness or disease in your baby mollies, such as lethargy, lack of appetite, or abnormal behavior. Treat any issues promptly to ensure their survival.
  • Keep an eye on their size and behavior: As your baby mollies grow, they may start to exhibit signs of aggression or other behavioral changes. Separate any aggressive or sick mollies from the rest of the group immediately.
  • Provide hiding places: Baby mollies need hiding places to feel safe and secure. Add some plants, caves or other decorations to the tank where they can hide and rest.
  • Avoid overcrowding: Do not overcrowd the tank with too many baby mollies as it can lead to stress, aggression and poor water quality. Make sure there is enough space for all of them to swim freely.
  • Be patient: Raising baby mollies takes time and patience. Do not expect instant results or quick growth. Keep providing them with the right environment and care, and they will flourish.

Taking care of baby mollies can be challenging but rewarding. By following these care tips, you can ensure your baby mollies grow up healthy, strong and happy.


In conclusion, while it is true that some mollies may eat their babies, it is important to understand that this behavior is not a reflection of their character or personality. Rather, it is a natural instinct that helps them ensure the survival of their species.

If you are keeping mollies in your aquarium, there are steps you can take to improve the chances of your fry surviving. These include providing plenty of hiding spots for the fry, feeding the adults a diet rich in protein, and separating the fry from the adults once they are born.

Overall, mollies are fascinating and complex creatures that require proper care and attention to thrive in a home aquarium. By understanding their behavior and needs, you can provide them with the best possible care and enjoy their beauty for years to come.

Molly Fish   Updated: March 11, 2023
avatar Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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