Guppies' Maternal Cannibalism: Why It Happens

why do female guppies eat their babies

Guppies are one of the most popular tropical fish in the fish-keeping hobby, but they do have one disturbing trait: they eat their babies. This behaviour is known as filial cannibalism and is exhibited by both male and female guppies. There are several reasons why guppies might eat their young, including hunger, a lack of parental instinct, and the need to replenish fat storage after giving birth. Guppies may also be weeding out weaker offspring to strengthen the gene pool. To prevent filial cannibalism, guppy keepers can separate the pregnant female guppy from the other fish in the aquarium using a breeding box or a separate tank.

Characteristics Values
Reason for eating babies Natural instinct, free food source, replenishing fat storage, continuation of strong offspring
What to do to prevent this Use a breeding box, manually separate the parent fish from the fry, use a breeding mesh, wait for them to grow bigger


Natural instinct

Guppies are known to engage in filial cannibalism, a behaviour where adult guppies eat their young. While there is no single explanation for this phenomenon, natural instinct is one of the factors that may contribute to it.

Guppies lack parental instinct and do not exhibit any parental care towards their offspring. This lack of parental instinct may be due to the competitive and stressful environment in which they live. Guppies are live-bearing fish, which means they give birth to free-swimming and independent young rather than laying eggs. The moment the fry are born, they are already on the menu for the adult guppies.

One theory suggests that guppies eat their young due to natural instinct and evolution's demand that only the fittest survive. Adult guppies may view the fry as a free source of food and eat those that are weak, small, or slow, ensuring the survival of the strongest offspring. This behaviour can also be seen as a way for the mother guppy to restore her energy and replenish her fat storage after pregnancy, as she spends a lot of energy and resources during the reproductive cycle.

Additionally, stress factors can play a role in triggering filial cannibalism. Stress can enhance the self-preservation instinct in adult guppies, leading them to eat their young. However, this behaviour is not limited to stressful conditions, as it has also been observed in non-stressful environments.

While the exact reasons for guppy filial cannibalism remain unclear, natural instinct plays a significant role in this puzzling behaviour.

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Free food source

Guppies are live-bearing fish, which means they do not lay eggs. They live in a competitive environment and engage in filial cannibalism or the act of eating their own young. One of the reasons they do this is because their offspring are a free food source.

Baby guppies are free food for their parents and the rest of the fish in the aquarium. They are, quite literally, free and easy prey as well as excellent sources of fat and protein. Guppies do not know that cannibalism is a horrifying act, so they view their young as a tasty and filling snack.

To prevent guppies from eating their young, fish keepers can use appropriate techniques and equipment such as a breeding box, a breeding mesh, or manual separation of the young from their parents. One of the simplest ways to prevent the fry from being eaten upon birth is to keep the female guppies isolated in a breeding enclosure. This box is usually made of plastic or glass and has holes on the underside that are big enough for the fry to slip through but too small for the female to use.

Another way to prevent guppies from eating their young is to set up a separate tank for the pregnant female. As the female is preparing to give birth, she should be placed into a separate aquarium, where she can give birth, and then extracted, leaving only the fry in the tank. This method is more expensive since it requires setting up a new tank with equipment such as a heater, filter, and lights.

In summary, guppies eat their young for several reasons, including the fact that they are a free and easily accessible food source. There are techniques to prevent this behaviour, such as using breeding boxes or setting up separate tanks, but these methods can be stressful for the fish and may not always be effective.

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Lack of parental instinct

Guppies are not known for their parenting skills. They lack parental instinct, and once the babies are born, they are already on the menu. Guppies are hungry after giving birth, and they see their young as a tasty snack. This behaviour is known as filial cannibalism, and it occurs in various insects and mammals, but it is particularly common in many fish species.

Guppies do not recognise their offspring and show no parental care. They will eat their young, especially those that are weak, small, and slow. This can be seen as a way to ensure only the fittest survive and strengthen the gene pool. Guppies live in a competitive environment, and their babies are free and easy prey.

Guppies also eat their young to restore their fat and energy reserves, which were depleted during pregnancy. The mother guppy, in particular, benefits from this as she spends a lot of energy and resources keeping her young safe during pregnancy.

Guppy keepers can prevent this behaviour by manually separating the adult guppies from their young. This can be done by using a breeding box or mesh, or by setting up a separate aquarium for the pregnant female. These methods ensure the babies have a safe space to grow and reduce the chances of them being eaten by their parents.


Continuation of strong offspring

Guppies are known to eat their young due to a variety of factors, including natural instinct, the desire for an easy food source, and the need to restore energy lost during pregnancy. One of the less common reasons for this behaviour is the continuation of strong offspring.

Adult guppies will eat their weak fry to ensure that only the strongest offspring survive. This is a form of natural selection, where the fittest individuals are given a better chance of survival. By eating their weak offspring, adult guppies are essentially curating the next generation to be more resilient and better equipped to face the challenges of their environment.

This behaviour is not unique to guppies and is observed in various insects and mammals, as well as many other fish species. Filial cannibalism, as it is called, is nature's way of ensuring the survival of the species by strengthening it through the culling of the weak.

Guppies, like many other species, lack strong parental instincts. They do not form emotional bonds with their offspring and do not exhibit protective behaviours towards them. This lack of parental care is one of the reasons why guppies eat their young without hesitation.

To prevent filial cannibalism, guppy owners can separate the pregnant female from the rest of the tank using a breeding box or mesh. This allows the female to give birth in a safe space, and the newborn fry can escape through small holes in the box or mesh that are too small for the adult guppies to fit through.

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Stress factors

One theory suggests that filial cannibalism is a result of a spill-over response prompted by stress factors, which enhances the self-preservation instinct of fish. However, this theory is not entirely satisfactory as the same behaviour can be observed in fish that are not kept in stressful conditions.

Stress can knock the self-preservation instinct in adult guppies, and they may view their fry as a tasty snack or an easy source of food. It is important to note that guppies do not distinguish their offspring from any other fry in the vicinity and show no parental care.

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Frequently asked questions

Female guppies eat their babies to replenish their fat storage and restore the energy lost during pregnancy.

Yes, one way to prevent female guppies from eating their babies is to separate the newborn fry and keep them in a separate tank.

The newborn fry can be introduced to the adult tank when they are big enough that the adults can no longer eat them.

Yes, male guppies also eat their babies.

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