Why do Guppies Eat their Babies?

As a seasoned guppy keeper, I’ve often found myself baffled by one intriguing aspect of these vibrant little creatures: their propensity to eat their own offspring.

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In this article, we’ll delve into the perplexing world of guppies, exploring the reasons behind this cannibalistic behavior, and sharing valuable insights I’ve gained throughout my fish-keeping journey.

Whether you’re a newbie to guppy care or a seasoned hobbyist, join me as we unravel the mysteries of these popular tropical fish and why they eat their own babies.

Reasons Guppies Eat Their Babies

Believe it or not, there are actually several explanations as to why guppies engage in this seemingly horrifying act. Let’s dive deep into these reasons to better understand our little aquatic friends.

  • Survival Instincts: Guppies are hardwired to constantly search for food. In the wild, this relentless focus on foraging ensures their survival. Consequently, they aren’t great at differentiating between their offspring and a tasty snack.
  • Stress: A stressed-out guppy can become aggressive, which may lead to attacking and consuming its young. Factors contributing to stress include tank size, water quality, or the presence of incompatible tank mates.
  • Lack of Nutrition: If your guppy is not receiving adequate nutrition from its diet, it may turn to its offspring as an alternative source of nutrition, driven by hunger and the need to survive.
  • Inadequate Space: If your guppies are kept in a cramped tank with limited space, competition for resources reaches its peak, which can result in adults preying on their own offspring.
  • Natural Selection: In some cases, guppies eating their fry may be part of nature’s way of weeding out weak and sickly young, ultimately ensuring the survival and propagation of the healthiest guppy genes.

Understanding these reasons helps create a more compassionate perspective, despite the shock factor of witnessing such behavior in your own tank. The good news is that there are preventative measures that can significantly reduce the likelihood of your guppies eating their babies. Let’s explore those next!

Prevent Guppies from Eating their Babies

While it’s clear that cannibalistic behavior in guppies can be attributed to various factors, we can take several measures to reduce the chances of our adult guppies consuming their fry.

1. Feeding Adults Regularly

One significant factor in preventing guppies from eating their babies is ensuring adult guppies receive a steady and consistent supply of nutritious food. Let’s examine how to keep your adults properly fed, reducing their need to resort to cannibalism.

  • Frequency: Feed adult guppies in small amounts at least two to three times per day. By spreading out meal times, you avoid overfeeding while also preventing hunger-driven aggressiveness.
  • Balanced Diet: Offer your guppies a rich and varied menu composed of high-quality flakes, pellets, and live or frozen food options like brine shrimp, daphnia, and bloodworms. This diversity will help meet their nutritional needs and minimize the chances of them turning to their offspring for sustenance.
  • Meal Planning: For a more precise feeding routine, consider setting specific times to feed your guppies every day. This schedule supports their natural biological clocks and feeding habits, making them better equipped to resist the temptation of their vulnerable fry.

Feeding your adult guppies consistently promotes optimal growth and health, and ultimately benefits both parents and offspring alike. By maintaining a disciplined feeding regimen and ensuring a nutrient-rich, varied diet, you reinforce the foundations of a harmonious, sustainable guppy ecosystem, where everyone can thrive.

2. Using a Breeding Box

Utilizing a breeding box is another highly effective approach to safeguard guppy fry from their voracious parents. Here’s how a breeding box works and how to make the most of it in your guppy tank:

  • Purpose: A breeding box is a small, perforated plastic container that floats within the aquarium or attaches to its side, creating a separate, confined space. The tiny holes allow water to circulate freely, but prevent adult guppies from entering and reaching the fry inside.
  • Introducing Pregnant Guppies: If you identify a pregnant female guppy, place her in the breeding box shortly before she gives birth. Once the babies are born, promptly remove the adult to prevent her from eating the newborn fry while confined in the box.
  • Feeding Fry in the Breeding Box: Ensure the fry receive a proper diet, including finely crushed flakes or specialized fry food, such as baby brine shrimp and microworms. Providing baby guppies with adequate nourishment while in the breeding box supports proper growth and development.
  • Moving Fry to a Larger Tank: Monitor the fry’s progress, and once they have grown enough to escape the adults’ predatory behavior, transfer them to the main tank or a separate grow-out tank. This allows more space for swimming and continued development.

Breeding boxes play a crucial role in increasing the survival rate of guppy fry, effectively keeping them away from adult guppies’ reach. However, it is essential to manage the breeding box correctly to ensure a healthy, thriving environment for your growing guppy babies.

3. Separating Pregnant Guppy

Proactively identifying and separating a pregnant guppy from the rest of the tank can greatly contribute to the safety of your future guppy fry. Let’s discuss the proper steps to take once you’ve identified a pregnant guppy.

  • Identifying a Pregnant Guppy: Look for a dark, triangular-shaped spot near the female guppy’s abdomen, called the “gravid spot.” As the pregnancy progresses, the spot will become more pronounced and darker, and her body will appear rounder.
  • Preparing a Separate Tank: To minimize stress on the pregnant guppy, set up a separate, well-furnished tank to house her. Ensure it has the appropriate conditions, including proper water quality, temperature, and plants for hiding spots.
  • Transferring Pregnant Guppy: Gently capture the pregnant guppy with a net and carefully introduce her to the separate tank. Monitor her closely during the transition period to ensure she’s adapting well to her new environment.
  • Post-Birth Care: Once the fry have been born, return the mother to the main tank, since she may eat her own offspring in the confined space. Care for the fry in the separate tank, providing them with a proper diet and adequate space to grow, until they are ready to join the main tank.

By separating the pregnant guppy from the main tank, you create a safer environment for both the mother and her babies, ensuring they get the best start at life. This proactive approach also decreases the chances of the adult guppies in the main tank turning their attention towards the vulnerable fry as a food source.

4. Using Live Plants and Hiding Places

Adding live plants and hiding spots to your guppy tank is another effective way of increasing the survival rate of guppy fry. It provides them with an essential refuge to escape the adults’ predatory tendencies. Let’s examine how to create a safe haven for your guppy babies.

  • Plant Selection: Opt for plants that offer dense cover and ample hiding places for the fry. Some popular choices include Java moss, Hornwort, Anacharis, and Guppy grass. These plants create a natural habitat for guppy fry to find shelter while they grow.
  • Arrangement: Position the live plants assortedly throughout the tank, allowing fry to seek cover and evade detection from the adults. A well-planted tank also oxygenates the water, promotes healthy bacteria growth, and enhances overall water quality.
  • Alternative Hiding Spots: In addition to live plants, consider adding artificial plants, caves, or decorations that provide small crevices for the fry to hide. These structures will offer additional layers of protection, granting the fry opportunities to escape the adults’ reach.
  • Cleaning and Maintenance: Live plants and hiding spots require proper maintenance to preserve water quality and support a healthy tank environment. Monitor the condition of the plants, trim and replace them as needed, and regularly inspect any additional hiding features to guarantee optimal conditions.

Introducing live plants and hiding spots to your guppy tank simulates their natural environment, enhances the overall appeal of your aquarium, and creates a sanctuary for the guppy fry. By providing sufficient cover and protection, you give your guppy babies the best possible chance to grow, develop, and flourish alongside the adult inhabitants of your tank.

5. Keeping Different Size Guppies Together

Interspersing guppies of various sizes within the tank can contribute to a balanced environment and help protect guppy fry. Here’s why mixing guppy sizes can benefit the younger fish in your tank:

  • Dispersed Attention: When different size guppies are kept together, the attention of the larger fish is spread across a broader range of potential targets, diminishing the focus on the vulnerable fry. This increases the guppy fry’s likelihood of survival.
  • Assessing Tank Compatibility: Ensure your guppies have adequate space and the appropriate conditions for their varying sizes. A well-maintained tank equipped to handle the coexistence of varying sizes will experience less stress and competition for resources, resulting in fewer instances of fry predation.
  • Tank Dynamics: Mixing guppy sizes will add diversity to the tank, encouraging fish to establish their territory and harmoniously coexist. As a result, a more balanced ecosystem is achieved, contributing to the overall health and well-being of your guppies, both big and small.
  • Selective Breeding: By nurturing varied sizes, colorations, and patterns of guppies in your tank, you can selectively breed the fish with the most desirable traits. This will enhance the quality and attractiveness of future guppy generations.

Mixing different size guppies in a single tank may seem counterintuitive; however, it can provide a safer haven for guppy fry while promoting a balanced and diverse environment for all your fish. By fostering harmony and healthy interaction among your tank’s inhabitants, you contribute to the proliferation of a more robust and vibrant guppy population.


While it may be initially shocking to witness the seemingly gruesome behavior of guppies eating their babies, understanding the reasons behind this natural instinct helps to create a more empathetic view of these fascinating fish.

Through consistent care, aquarium management, and implementing preventative measures, you can significantly improve the chances of your guppy fry thriving alongside their adult counterparts.

As we gain insight into the peculiar world of guppies, we strengthen our capacity to nurture and maintain a healthy, dynamic ecosystem that we can appreciate and admire for years to come.

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