Why Is My Guppy Fry Not Growing? 7 Solid Reasons

One of the significant concerns that irritate most fish owners is its fry growth. In this article, I’m going to answer a fascinating question: why is my guppy fry not growing? This article will highlight all the points and factors that can stunt your guppy fry growth. Typically, stunts in the guppy fry growth usually happen due to space issues in the tank. 

Let’sLet’s first learn why my guppy fry is not growing, and after that, we will share some tips that will allow you to fix issues if needed. Many factors can stunt and manifest young guppy growth.

Article Contents

Why Is My Guppy Fry Not Growing?

why is my guppy fry not growing
why is my guppy fry not growing

In a small tank, a guppy fry growth will be stunted. Overcrowded tanks tend to be the main culprit that stops the growth of fries. Not finding food or competing over food in a crowded tank may also result in stunted growth. 

In rare cases, genetic issues or inappropriate water quality stop fish growth. If you find your guppy fish not thriving & growing well, then it is not an excuse to throw them away. 

It is essential to identify all the factors that are preventing your guppy fry from growing. Understanding the element will help you take steps and fix the issue to enhance their growth. Let’sLet’s learn some factors that contribute to preventing guppy fry from growing.

7 Factors That Stops Guppy Fry Growth

Water Parameters

It is essential to keep the water parameters like temperature, pH level, & its hardness maintained. 

If anything goes wrong in the water parameter, the fry suffers consequences. They will either die or have a severe effect on their health, including stunted or slow growth.


Sometimes it has been noticed that some genetic anomalies prevent guppies from growing. Guppy fish suffering from genetic issues is hard to resolve. 

Believe it or not, but if it’s just bad luck and nothing else. If this is the case, you can try again because adult guppies breed very quickly and easily.

Water Change

It is important to occasionally change your tank water because the person who don’t change its tank water regularly often deteriorates its quality.

The water that has deteriorated and has not been appropriately changed will stress the guppy fry out while limiting its growth rate.


In an overcrowded tank, a guppy fry will not be able to locate or complete over food. Feeding them poor-quality food may also stunt their growth. 

It is essential to feed your guppy fries from time to time and make sure to keep the quantity satisfying according to their hefty appetite.


Most people fool themselves by thinking that keeping a fish in a big tank will allow them to grow to their full size while keeping them in a small tank will limit their growth which is not valid. 

Just to you aware, no fish can deliberately enhance or limit its growth according to the size of the aquarium. However, the size of the tank or the space can indirectly impact their health and maturation. 

Keeping them in a bit of space often stresses guppies out. If your guppy fries cannot swim freely as they would like, it will stress them out. Stress and the toxin found in small tanks alone are enough to reduce your guppy fries’ growth rate ultimately. 

Whereas keeping in a large tank will expose your guppy fries to threat. A large and a guppy fry often find it very difficult to locate food. 

Plus, lots of energy e gets spent in this process, which can also be why their growth rate is slow.


There are tons of toxins that can be a death sentence to Guppy fries. Toxin like copper, chlorine, ammonia, nitrites and more may completely stop or stunt your guppy fries’ growth.


Most times, the owner often gets confused about counting the guppy fry. You may have missed the new offspring to count.

It is essential to approach the aquarium slowly and count guppy fry in your tank every day. If you see the number going up, then maybe you were looking at different guppy fry previously that made you suspicious about its growth. 

Adult guppy breeds very quickly and often give birth to new offspring every few weeks. So it may be possible that you are looking at new fry each day or each week.

7 Tips if Your Guppy Fry isn’t Growing Properly

7 tips if your guppy fry isn't growing properly
7 tips if your guppy fry isn’t growing properly

It’sIt’s not going to take a considerable effort or much time to help your fry growing property. 

Many tips can help you keep your guppy fry healthy, but here we will discuss the bonuses and the fixes that help create a stress-free environment with appropriate conditions to boost their growth. 

Make sure to double-check all the parameters, factors, and tips to ensure all the things being ruled out that could have blocked your guppy fry growth.

Feed Them Proper Diet. 

The first tip that is very common in all the articles, forums and highly recommended by veterinarians is picking the proper diet.

If you have been feeding your guppies a poor quality diet that doesn’t meet their nutritional needs, then maybe this is the cause of underlying stunted growth in fries. 

Guppy fry cannot grow and satisfy their nutritional needs if their diet doesn’t meet its requirement. Naturally, a fish tends to be very small, which is why you should grind their food entirely before sprinkling it all over the aquarium at a time. 

The food should be in the size that fits in their mouth. It is also recommended to keep the adult guppy fish in a separate tank away from the fry so that they won’t have to complete the food.

Provide A Stress-Free Environment.

The fries are vulnerable to the side effects of stress. The guppy fry will also get stressed if they are kept in a small or too large tank.

It is essential to always maintain a clean tank for them and keep the parameters appropriate all the time. If you see any signs of stress in your guppy fry, consider adding some decoration plants & hides. 

Plants inside the tank will help your guppy evade Predators very easily while alleviating some of its stress. It is essential to make hiding places inside their aquarium to hide whenever they feel vulnerable to find ease permanently. 

A hiding place is a good idea if the guppy fry shares a tank with adult fish. Plus, bullying can also be the result of keeping fry with adult fish.

Keep Them In A Controlled Suitable Water Parameter. 

It is essential to conduct a good water change. It is necessary to change at least 30% of the water once a week. I don’t know if you know this or not, but not all the filtration systems help keep the water clean. 

Occasional water change is effective at simply eliminating the water pollutants. It is necessary to change the water because, in most cases, even an efficient filtration system cannot continuously keep the water clean enough to suit fish health and wellbeing. 

Make sure to check the ammonia spikes along with the other stuff like toxins of your aquarium. 

If you don’tdon’t know, then let me tell you the suitable water parameter for your guppy fry is between 7.0 to 7.2 to pH level.

The temperature inside their tank should be around 80 degrees Fahrenheit. Try to keep the nitrites, the nitrates, and the ammonia as minimal as possible. 

Suppose you find it difficult to monitor those parameters. In that case, I recommend you get a good quality API aquarium test kit that can help you test the water and adjust the parameters according to the guppy fry needs. 

Remember that an efficient filtration system and regular water change will not be sufficient to suit their needs. 

It would help if you considered scrubbing the decoration awaiting the walls of the aquarium, eliminating any leftover foods, waste, and debris to prevent the concentration of toxins from spiking. 

I have seen many people debating using a conditioner to control the level of talking inside the aquarium, but I would highly recommend you avoid that. Depending upon your situation and under professional supervision, you can use a conditioner.

Provide Them Enough Space. 

It is essential to keep them in a medium-sized tank because too small or too large will stunt their growth anyway. In a small tank, the fry will feel stress. On the other hand, in a large tan, fr will not locate the foods. 

To be on the safe side, get at least a 5-gallon aquarium in case there are many guppy offspring. In most cases, I have seen people keeping their guppy fry in one or a half-gallon of water which is an apparent cause of stunted growth. 

An aquarium of 5 gallons will give your fries ample space to swim and explore. Always have an aquarium that is not understocked or overstocked. 

Under or Overstocked tanks will result in the guppy fries competing with each other over food. This can also limit some of your fry’s growth rate. Other than that, if they don’t starve to death, they will be eaten by adult fish.

Set The Right Temperature Inside The Tank. 

The temperature seems to be the primary fix for owners with fry stunted growth in all the parameters. Guppy fish usually live in the tank water with a temperature between 70 to 80 degrees Fahrenheit. 

According to many experts, 80 degrees Fahrenheit seems the ideal temperature for guppy fry growth and wellbeing. Keeping guppy fry at 80 degrees Fahrenheit will also boost metabolism, resulting in a faster growth rate. 

Make sure to keep the temperature consistently stable. Any change in the temperature causes stress and stunts your fry growth. There are lots of devices that can help you monitor and set the temperature to 80 degrees Fahrenheit. 

I recommend you get a good-quality heater with a flat surface that sits at the bottom of the aquarium. It will help you in keeping the temperature of the water maintained. Plus, this kind of device tends to be very easy to use while being compact in size and durable.


How Long Does it Take For Guppy Fry to Grow?

Guppy fry takes almost 4-6 months to reach adulthood. Some guppy fry can take eight months to grow fully if kept in the wrong parameters or poor quality diet. 

Keeping them in a conducive environment, plenty of space, high-quality food, and the correct water parameters will boost its growth. In most cases, despite the best effort, care, proper parameters, and condition, some guppy fry fails to grow and often die due to epigenetics. 

Although guppy fries tend to grow fully in 6 months, some of them can take almost a year if they are suffering from any infection or disease.

How To Feed Guppy Fry?

Guppy fry tends to have more enormous appetites and should be fed more frequently than adult onesies. It is essential to provide guppy fry at least eight times a day in a sufficient quantity to satisfy their need and appetite. 

Without a sufficient amount of food, they won’t able to grow fully. Plus, it is essential to keep the high diet quality because nutrition is needed to fulfill all its requirements for a faster growth rate. 

If you keep them at 80 degrees Fahrenheit temperature, their metabolism will be speedy. Too much ammonia in the water can stunt their growth. Overfeeding can also too.


The process of breeding guppy fish and its development is callous for some noobs, which is why we have shared a comprehensive guide on how to breed guppy fish. Most times, a slow growth rate or stunted growth in guppy fries can be frustrating. 

It is essential to stick to a routine that works for you, making the whole process easier. It’sIt’s necessary to keep the parameters of their aquarium maintained and monitored. 

Factors like wrong parameters, small aquariums, wrong temperatures, and more have to do with your guppy fry growth rate. 

It is essential to pay close attention to all the factors and fix any issues if found. It is necessary to keep the parameter maintained to mitigate stress.

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