Guppy Breeding: Why No Fry?

why are my guppies not breeding

Guppies are known to be prolific breeders, but several factors can prevent them from breeding. One of the most common reasons is poor water conditions. Guppies require specific water temperatures, and the water should be regularly replaced with fresh, oxygenated water to prevent stress. Additionally, guppies need a suitable environment with plenty of plants to provide hiding places for newborn babies, protecting them from larger fish. Another reason for a lack of breeding could be that the guppies are too old or stressed. Guppies also need the right partner to breed, and a single pair kept in isolation may experience stress, so it is recommended to have multiple females for one male.


Poor water conditions

Guppies are a species of tropical freshwater fish that are renowned for their dynamic hues, diverse patterns, and the vivacious energy they bring to any aquarium. They are also relatively easy to breed, but they won't breed in poor water conditions.

To create the right water conditions for breeding, you should ensure the water is well-conditioned, clean, and dechlorinated. Regular water changes – about 25% to 50% every week – will help maintain optimal water quality. The pH level should ideally be between 6.8 and 7.8, and it's crucial to keep a check on the ammonia, nitrite, and nitrate levels in the tank. Any imbalance can lead to health complications for your fish.

Guppies are tropical fish, so they thrive in warmer water. A temperature range between 72°F and 82°F (22°C – 28°C) is ideal, and sudden fluctuations in temperature can be stressful for guppies. You can use an aquarium heater and a thermometer to regulate and monitor the temperature effectively.

Guppies enjoy pH levels at 7.0 or greater and like hard water with good amounts of calcium, magnesium, and other essential minerals. If your water is naturally soft, you can add Wonder Shell to your aquarium to raise the water hardness and add minerals.

In addition to water quality and temperature, the flow of the water is also important. Reduce the flow if it ripples in the water, as this can scare the guppies.


Incorrect identification of male and female guppies

One of the reasons why your guppies are not breeding could be the incorrect identification of male and female guppies. It is important to distinguish between male and female guppies, as it plays a crucial role in maintaining a harmonious tank environment and successful breeding. While it is challenging to identify the sex of guppies when they are young, there are several physical attributes and behavioural traits that can help in determining their gender.

Body Shape and Size

Male guppies usually have slender, long bodies, while female guppies are rounder and larger, sometimes twice the size of male guppies. Female guppies can grow up to 2 ⅛ inches (6 cm), while males typically reach a maximum length of 1 ⅛ inches (3 cm). The difference in size between the sexes is often noticeable early on.

Colouring and Patterns

Male guppies tend to be more colourful than females, with their bodies adorned in bright colours and patterns such as orange, blue, violet, green, black, and white spots and stripes. These vibrant colours and patterns are used to attract female mates. However, it is important to note that some types of guppies have females that are also quite colourful, so it is advisable to consider other physical markers for accurate gender identification.

Gravid Spot

The presence or absence of the gravid spot is a reliable indicator of a guppy's gender. The gravid spot is a dark spot located on the underside of the female guppy's body, near the tail. This spot becomes darker and larger as the female progresses through pregnancy. Male guppies do not possess this feature.

Dorsal Fin

The dorsal fin, located on the top of the guppy's body, differs between the sexes. Male guppies have long dorsal fins that trail in the water, while female dorsal fins are noticeably shorter and do not trail as they swim.

Tail Fin (Caudal)

Male guppies have wide, long, and colourful caudal fins, often with elaborate patterns. In contrast, female guppies have shorter caudal fins that are not as wide or long as those of males.

Anal Fin

The anal fin, located under the guppy, just before the tail fin, also differs in shape between the sexes. Male guppies have a long and narrow anal fin with a slightly pointed end, which is used for insemination. Female guppies, on the other hand, have a shorter, triangular-shaped anal fin. The gravid spot is located right above the female's anal fin.

Behavioural Clues

Observing the behaviour of guppies can provide crucial clues to their gender. Male guppies tend to be more active and exhibit distinct courtship behaviours, such as chasing females and performing the "sigmoid display," where they curve their bodies into an S shape. Female guppies, on the other hand, display calmer swimming patterns and may exhibit unique behaviours when pregnant, such as retreating to the corners of the tank and refusing food.

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Guppies are too old

Guppies are considered to be one of the least expensive and most plentiful tropical fish, and they are popular for their brilliant colours, hardiness, ease of breeding, and beautiful physical display. However, one of the reasons your guppies are not breeding could be that they are too old.

Guppies have a rapid maturity rate, and females begin breeding at around an inch in length. Male guppies are smaller than females, reaching an average length of 1.5 inches. While age is not the only factor that determines the size of a guppy, it is a significant one. Therefore, if your guppies are significantly larger than the average adult size, they may be too old to breed.

Additionally, guppies have a relatively short lifespan, with a life expectancy of around two years in captivity. So, if your guppies are approaching or beyond this age, they may be too old to breed successfully.

It is worth noting that guppies are typically very prolific breeders, and they will breed rapidly when left to their own devices, even in less-than-ideal conditions. Therefore, if your guppies are not breeding, old age could be a contributing factor, especially if other conditions, such as water quality and temperature, are favourable.

To summarise, while guppies are generally hardy and easy to breed, they do have a relatively short lifespan and mature quickly. If your guppies are older or larger than average, they may be beyond their breeding years, which could be the reason for their lack of reproductive activity.

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Lack of hiding places for newborn guppies

Guppies are a popular choice for fish enthusiasts due to their vibrant colours, cute faces, and small size. However, one common issue that guppy owners face is a lack of breeding. One of the critical factors for successful guppy breeding is providing ample hiding spots for newborn guppies. Guppies are opportunistic feeders, and in the absence of adequate hiding spots, they may resort to cannibalism, eating their young. Therefore, creating a safe environment for newborn guppies is essential.

Guppies are known to eat their babies, a behaviour referred to as cannibalism. While not all guppies exhibit this behaviour, it is essential to understand the factors that contribute to it. One of the primary factors is the lack of hiding spots or inadequate space in the tank. Guppy fry needs to be protected from predation, and without sufficient hiding places, they become easy targets for their parents and other larger fish in the tank.

To prevent this, guppy owners should ensure their tank has plenty of plants, both live and artificial, to provide hiding spots and a natural environment for the newborn guppies. Plants such as Java moss, Java fern, and Anubias are excellent choices as they are easy to care for and provide ample hiding spaces. In addition to plants, decorations such as caves, rocks, and driftwood can also create hiding spots while adding visual interest to the tank. It is important to choose decorations that are suitable for the tank size and avoid those with sharp edges or small holes that can trap the guppy fry.

Another way to provide hiding spots is by creating natural hiding places using materials such as coconut shells, terracotta pots, or PVC pipes. These materials can be cleaned and sterilised and provide a natural-looking environment for the guppies. It is crucial to place hiding spots in different areas of the tank to avoid competition and ensure open spaces for swimming and exploration. Additionally, maintaining good water quality and keeping the tank clean are essential, as dirty water can lead to stress and disease, further discouraging guppies from using the available hiding spots.

In conclusion, providing ample hiding spots for newborn guppies is vital to successful breeding and the survival of the fry. By creating a safe and comfortable environment, guppy owners can prevent cannibalism and reduce stress levels in their guppy community.



Guppies are quite responsive to environmental shifts, and stress can be caused by several factors, including:

Poor Water Quality

High levels of ammonia, nitrites, or nitrates, as well as extreme pH levels, can cause stress and health issues. Guppies are tropical fish and need a stable and suitable temperature range of 72-82°F (22-28°C). Fluctuations or extremes in temperature can be stressful for them.

Inadequate Hiding Spots

Guppies need safe hiding spots in their environment, such as plants or caves, to feel secure and reduce stress. A lack of hiding spots can make them feel vulnerable and exposed, leading to increased stress levels.


Insufficient space can lead to stress, as guppies need ample room to swim and explore. Overcrowding can also result in territorial behaviour and aggression among the fish, further adding to their stress levels.

Aggressive Tank Mates

Some fish species can be aggressive towards guppies, causing stress and even injury. Guppies are peaceful fish and won't fight back, so it's important to carefully select compatible tank mates to avoid this issue.

Loud Noises or Vibrations

Guppies are sensitive to loud noises and vibrations, which can be a source of stress. Placing their tank in a quiet, stable location can help reduce this particular stressor.

Poor Lighting

Guppies require a balance of light and darkness to maintain a healthy circadian rhythm. Constant lighting or insufficient lighting can disrupt their natural sleep patterns and cause stress.

Other Factors

Other potential causes of stress in guppies include transportation or handling, inadequate diet, and rapid temperature fluctuations.

Frequently asked questions

Guppies need the right water conditions to breed. They also need the right partner, and if they are too old, they may not mate.

Guppies need clean water with the right temperature (75-82 degrees Fahrenheit or 24.50 to 26.50 Celsius) and oxygen levels. They also require plenty of hiding places, such as plants, to feel safe.

Guppies need to be correctly identified as male or female. They should be kept in a small group with more females than males to prevent the male from becoming too aggressive.

Guppies may not breed if they are stressed due to poor water conditions, lack of oxygen, or an unnatural environment. They may also be too young or not ready to breed yet.

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