How Many Guppy Fry Will Survive? (Survival Rate Explained)

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One of the questions I kept asking myself when growing guppies was how many fry are expected to survive once they are born. In other words, I wanted to know the survival rate of guppy fry. Fortunately, over the years, I gained some experience in this field.

This table demonstrates how many guppy fry are expected to survive, depending on their growing environment:

Main Tank0-15%
Breeding Boxes15-25%
Breeding Tanks30-40%

As we move forward, I will elaborate on the survival rates of guppy fry in different breeding environments. Then, I’ll share some tips on how to increase those numbers.

Still curious? Feel free to check my complete guide on guppy fry. There, I discussed how to care for guppy fry, what they eat, how often to feed them, their growth stages, and much more.

How Many Guppy Fry Will Survive?

Guppies can produce as many as 200 fry at a time.[1] But you can’t expect them all to survive. But how many baby guppies can you realistically save? Well, it depends on the situation:

1. Survival Rates In The Main Tank

If your baby guppies have to share an aquarium with adult fish with no hiding places, you may lose them all. Even if you have a guppy-only tank, their chances of survival are meager. This is because guppies eat their offspring.

Filial cannibalism is one of the most significant attributes of this species, which is why many keep them separated for at least six weeks. You are also encouraged to separate the pregnant mother before she gives birth to prevent her tankmates from harassing her to death.[2]

Once she pushes the fry out, she should return to the main tank. Otherwise, she will eat all the fry. You can enhance a guppy fry’s chances of survival by increasing the number of hiding places in the tank.

If the main tank has plenty of hiding places, such as plants and decorations, the guppy fry survival rates jump to 10 to 15 percent. As a rule of thumb, the more hiding places you have, the higher the survival rates are.

But even then, you are going to lose a lot of babies. Fry in a separate tank can still die. However, their survival rate is tied to the conditions in their aquatic environment.

2. Survival Rates In A Breeding Box

The primary consideration here is the breeding box’s size and how long the guppy fry are kept in it. If the box is wide enough and occupies most of the aquarium’s length, the survival rates are pretty decent and range from 15 to 25 percent.

But you can’t expect these many fry to survive if the conditions in the breeding box are crowded and the guppies are kept there for a few weeks. The numbers can quickly drop down to 0 percent if the conditions are not taken care of.

A breeder box isn’t necessarily ideal. Breeder boxes induce stress in fish. This is why aquarists wait until a pregnant guppy is close to giving birth before moving it to a breeder box. They want to limit the amount of time it spends in the box.

If the female has refused to give birth, it is common practice to reintroduce it to the main tank within a day or two. Baby guppies are smaller than adult fish. Therefore, they can stay in the breeder box for several weeks.

However, the experience can lower their mortality rate. Some aquarists hate breeder boxes because they have a reputation for stunting the growth of baby fish. This is why they send the babies to the main tank after one or two weeks.

3. Survival Rates In A Breeding Tank

The average guppy fry survival rate in a breeding tank stands at 20 percent.[3] But you won’t find any concrete figures backing that number. From my experience, when taking care of the water conditions, the survival rate is closer to 30 to 40 percent.

To maximize the survival chances, stick with these water parameters:

  • Temperature: 78-80 degrees F
  • pH: 6.8-7.6
  • Hardness: 8-12 dGH
  • Ammonia: 0 ppm
  • Nitrites: 0 ppm
  • Nitrates: <20 ppm

To measure the pH, ammonia, nitrates, and nitrites, I personally use the API Aquarium Test Kit (link to Amazon). That is probably the most accurate bundle out there. It also lasts for eight hundred measures, so it is definitely worth the investment.

I also recommend using an air pump in a guppy fry tank, as I previously discussed here. These tiny creatures consume plenty of oxygen and require aeration. Stagnant water will stunt their growth and lower their survival rates.

What Affects The Guppy Fry Survival Rate?

As you can see, the environment in which the guppy fry are kept directly impacts their survival rates. Generally, more fry are expected to survive in breeding tanks than breeding boxes.

But why is it difficult to raise these numbers to 80 and even 90 percent? Well, that is because other factors play a role in this equation.

Guppies are not like bettas. People expect roughly 90 percent of betta fry to survive.[4] But the statistics are not quite as clear where guppies are concerned. Anecdotal evidence is equally diverse.

Some people will raise all their babies to adulthood. Others will lose them all. Most people fall somewhere in between. But even then, opinions vary widely because guppy fry survival rates are shaped by various factors, including:

1. Genetic Abnormalities

This is the trickiest component because you cannot change it. Some guppies have genetic anomalies that predispose them to early deaths. If you have a well-maintained tank, but every fry dies, you can blame genetics.

Unfortunately, your only option is to get new breeding pairs in this situation. That means either culling the pre-existing guppy population or giving them away.

Bear in mind that you cannot blame premature deaths among guppy fry on genetic anomalies unless you’ve created a conducive environment in the breeding tank.

2. Parental Health Issues

The parents’ health can have a significant impact on the health of the babies. Diseased parents are more likely to produce sick fry that die within the first few hours or days. This, of course, assumes that the females gave birth successfully.

They could just as easily abort their pregnancies. Genetics plays a role in this area as well. Guppies with genetic deformities will produce deformed fry that are more likely to die at birth.

3. Swimming Space

How much space do the baby guppies have in the tank? Crowded conditions are just as dangerous to guppy fry as they are to adult guppies. The stress will kill them faster than you realize, especially if the crowded conditions introduce an oxygen deficiency.

People don’t expect fry to struggle with crowded conditions because of their small size. Unfortunately, because of their small size, beginners are more likely to rear guppy fry in tiny containers.

However, crowded conditions are the least of your worries. Guppy fry have a challenge that their parents rarely face. You can also kill them by giving the creatures too much space.

Because they are so small and vulnerable, they will expend more energy than they can afford to cross the aquarium to find food. In the best-case scenario, the stress will simply stunt their growth. In the worst case, the creatures will die.

That is why it is best to provide 0.5 to 1 gallon for each guppy fry.[5] Half a gallon is best for the early stages. One gallon per fry is the best choice after two to three months, as the guppy fry grow.

4. Hygiene Status

If ammonia can burn an adult guppy’s body until it changes color, you can rest assured that the substance has an enormous impact on the tiny fry. Hygiene is an essential component of a breeding tank.

Do you change the water regularly? How much water do you change? Are you changing so much water that the babies are dying because of the drastic shifts in parameters?

Is the ammonia concentration spiking because you have gone weeks without changing the water? What about the new water? Did you treat it with a conditioner, or are your fry dying because of the chlorine?

I also suggest that you remove leftovers and dead fry. These can quickly decay and interfere with the water chemistry.

A dirty tank will kill all the baby guppies under your care. They cannot tolerate a poorly maintained tank. The dirtier the tank, the higher the mortality rate.

5. The Water Parameters

Guppy fry require temperatures of 78 degrees F to 80 degrees F and a pH of 6.8 to 7.6. You should also give them an effective filter (that won’t suck them in) and eight to twelve hours of daylight.

Extreme parameters can kill all your babies within days. That includes harsh, continuous lighting that doesn’t allow the babies to rest.

6. Food And Feeding Frequencies

It doesn’t take much for baby guppies to starve. They should be fed between four to eight meals a day as they are born. They may die in large numbers if your tank doesn’t have enough food or algae.

After two months, you can lower the frequency to four meals a day and twice a day after five months. For more information, please check this article, where I discussed what guppy fry eat. I also included some valuable videos and instructions.

As you can see, the survival rate in a guppy fry breeding tank depends on too many factors. Don’t expect the survival rate in your aquarium to match the survival rate of another person’s aquarium. The conditions will determine the fate of your baby guppies.

If you found this article helpful, these may also interest you:

Pro tip: If your guppies breed frequently, you’ll need to know a little more about that process. Feel free to check my complete guide on pregnant guppies.


The guppy fry survival rate depends on numerous factors. Some of them are out of your control, such as genetics. Also, in many cases, guppy fry won’t survive because their parents were initially sick or deformed.

But you still have control in some areas. For example, more fry will survive if the conditions aren’t crowded, there are plenty of hiding places, and the feeding is in the correct frequencies.

As a rule of thumb, the survival rate varies between 0 to 40 percent. You can go higher by adjusting the water parameters, including the pH, ammonia, nitrates, and nitrites. It would help if you also kept the temperature between 78 and 80 degrees F.