Do Guppies Change Gender?

Many fish species can perform a gender change. Fishes change their gender to eliminate the scarcity of another gender and comfortably continue the breeding process. However, not all fish can change their gender in such a situation, and we will know that is guppy fish included in this list. So, Do guppies change gender? Let us find out.

There is no research that scientifically proves that guppy can change gender. However, many fish species change gender when circumstances require it. So, looking at that point, it is theoretically possible that guppies do change gender when there is a need for that.

We will discuss why fish change their gender and also how to differentiate between male and female guppies in this article. Also, we will discuss ways to control the population of guppies in the aquarium. So, let us get into it.

Why do fish change their gender?

Fishes usually change their gender to ensure their genetic diversity continues to survive and adapt well to the environment.

The presence of both male and female fish is necessary to perform the reproduction process.

Many fishes change their gender if there is a scarcity of another gender.

Fishes can change their sex naturally, also known as a hermaphrodite.

In hermaphrodite, fishes can wholly or partially possess both female and male reproductive organs.

There are three ways of fish changing gender for increasing their survival rate:

  1. Protogynous (Female to male)
  2. Protandrous (Male to Female)
  3. Bi-directional (Back and forth according to environmental circumstances) 

In protogynous, larger male fish will be territorial, and the small female fish will lay eggs only for the male fish who has spawned and protect spawning size.

Once the female gets bigger, and the male fish passes away, the female fish takes the place of the male fish.

It is commonly found in gobi fish.

There is a need for a big female fish and two small male fish for survival in protandrous.

The reason behind it is that female fish are more fertile, and male fishes are capable of spreading sperm.

In bi-directional, fishes change their gender back and forth according to the environmental circumstances.

Are all guppies born female?

We can easily get confused by the guppy fry’s appearance and make mistakes by thinking that all guppies are born female.

All guppies are not born female. When the guppy fry is born, they have plane color and don’t have any indicators to detect if they are male or female.

This all confuses us, and we think that all guppies are born female, and when the male guppy gets 3-4 weeks old and develops a differentiating feature, we think that the female guppy has been converted to a male one.

How to differentiate guppies’ gender?

It is not hard to differentiate between male and female guppy.

Male guppies have more colors than female guppies.

The reason behind male guppies being more colorful and attractive is chromosomes.

Male guppies have chromosomes that only get passed to male guppies and are inherited almost unchanged. The chromosomes are not passed to female guppies.

This difference of chromosomes is the key to differentiating between male and female guppy.

You can differentiate between male and female guppies based on bright and more color when they are 4-5 weeks old, as guppy fry will look plane in color when get born.

Also read: Why Do Guppies Lose Their Color?

The other ways to differentiate male and female guppy are:

  1. Female guppies are bigger than male guppies.
  2. Female guppies have a gravid spot behind their anal fin.
  3. You can easily detect gonopodium in male guppies.


You can differ between male and female guppies by their size.

Female guppies are larger than male guppies in size.

Male guppies can grow up to 0.6-1.4 inches in size, whereas female guppies can grow up to 1.2-2.4 inches.

By looking at the size of your guppy fish, you can easily differentiate between male guppies and female guppies.

Gravid spot

Female guppies have a gravid spot behind the anal fin of their body.

The gravid spot is also the way to find if your female guppy is pregnant or not.

Your female guppy’s gravid spot will get darker and will extend when your guppy is pregnant.

The gravid spot is where female guppies hold their fry while they are pregnant.

Looking for a gravid spot is another way to differentiate between male and female guppies, as the gravid spot is only present in female guppies and not in male guppies.


Like gravid spot in female guppy becomes helpful to detect female guppy, gonopodium makes it easier to detect male guppies.

Male guppies have an external structure known as a gonopodium, which they use to transfer the sperm in female guppies.

If you look closely, you can detect gonopodium in your male guppies.

You can look for gonopodium in your male guppies when they are about 4-5 weeks old.

Why is it essential to detect gender early in guppies?

Guppies are excellent breeders, and if kept male and female guppies in the same tank, they can breed out of control.

Excessive breeding is the main factor behind detecting and separating the gender in the early stages.

Male guppies can mate by the time they get one month old.

Female guppies can give birth to fry when they get three months old.

Keeping male and female guppies in the same tank will result in the overpopulation of guppies in your aquarium.

Female guppy can release up to 200 guppy fry at a time. And female guppies can get pregnant every 30 days if the water condition is good.

Separating them before their maturing age is essential if you don’t want to overcrowd your aquarium with guppies.

How to solve the overpopulation problem in guppies?

Guppies could breed out of control if males and females were kept together in the same aquarium.

Overbreeding will soon get your guppies aquarium overcrowded.

An overcrowded tank can cause various problems like:

  1. Lack of space for guppies to live comfortably.
  2. Deficiency of oxygen
  3. Tank is getting dirty soon.
  4. Lack of food

Ways to control the population of guppies are:

  1. Separate male and female guppies.
  2. Let the guppy fry live in your home aquarium when they are born.
  3. Adding female betta will help reduce the guppy fry population.
  4. Remove all hiding spots you have in your guppies aquarium.


Separating your male and female guppies and keeping only one gender of guppy in your tank will help you eliminate the problem of overpopulation.

Keeping only female guppies rather than only male guppies is good.

Male guppies can get aggressive and territorial if there are no female guppies in the tank.

Keeeping guppy fry with an adult guppy

Letting guppy fry live with your adult guppies and other tankmates will help you reduce the population of guppy fry.

Adult guppies and other tankmates will see the guppy fry as food and feed on them.

Even a mother guppy will not get back when it comes to feeding on their fry.

Also read: Can Guppy Fry Survive In Community Tank?

Adding female betta fish

Adding female betta fish will also help reduce the population of guppy fry.

Bettas are carnivore fish species and will happily feed on guppy fry.

Make sure not to add male betta in your guppies aquarium, as it will make the situation worse than better.

Male betta fish will bully your adult guppies and can also hunt them down.

Also read: Can Guppies Live With Betta Fish?

Removing hiding spots

Removing all hiding spots from your guppies aquarium is a good way to reduce the population of guppy fry.

Removing hiding places will prevent your guppy fry from hiding, and adult guppy and other tankmates will find it easy to detect the guppy fry and feed on them.

These all are some ways to prevent your guppies aquarium from getting overcrowded.

The best way to control the population is to separate the male and female guppies so that they don’t get to breed.


Many fishes change their gender when the circumstances need it.

If there is a scarcity of one gender to perform the breeding process, then the other gender changes to the scarce gender.

It is controversial regarding guppy, but theoretically, guppies can change their gender according to circumstances.

Reference: NCBI, ResearchGate, Journals, JSTOR

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