Can Guppy Fish Change Gender?

Guppy fish

There is a lot of conflicting information online as to guppy fish sex. A lot believe that they are all females, some say guppy fish can change their gender while some even think of them as hermaphrodites. 

As a new hobbyist, all these can be confusing. You might be curious to ask if all your guppies are females, how they reproduce, and if at all they are not all females how then do you differentiate the male guppies from the female.

In this article, you will get to know the real fact about guppy fish and if they can change their gender or not. Read along as we debunk any of those myths about guppy fish that is causing a lot of debates online.

Can Guppy Fish Change Gender?

The answer is a simple no. A Guppy fish can not change its gender. The popular belief that all guppies are born female and some later change their gender is only because the visual difference between the male and female guppies is hard to differentiate.

They all look almost the same, but as they mature and grow, the male features become prominent. That is the reason behind the myth that female guppies are the ones changing their gender.

Most of the male and female distinctive features appear from week 4. You can wait for these features to be visibly clear before you sex your guppies. Some male guppies develop their features much later than others, they might still look like female guppies for longer than others. After one month of age, all features are more obvious and you can tell a male from a female Guppy fish.

Are Guppy Fishes Hermaphrodites?

No, guppies are not hermaphrodites. A male guppy has to mate with a female guppy to fertilize her eggs and produce frys.

The female guppy has a unique ability to store the male guppy’s sperm for seven months or more, hence why some people might rule out some taught if a guppy happens to give birth without coming in contact with a male guppy. 

How to Differentiate a Male and Female Guppy Fish

It can be hard to differentiate a male from a female Guppy anytime below 4 weeks of age due to their subtle difference. At 4 weeks, the difference between the male and female begins to get obvious and you can tell which from which.

Once you can differentiate your colourful and lively guppies, you can separate them since they are prolific. Guppies reproduce easily and rapidly and it makes them live young. They also tend to devour the younger once if the chance permits them. 

To differentiate a male guppy from a female Guppy isn’t much of a big deal. Once you know the features that differentiate them. You can tell a male guppy from a female in four different ways. They are;

– From Their Fins and Colors

The male guppy appears more colourful than the female, with his body having more splashes of various colours. The bright colour of the male makes it more attractive for the females to come to them for mating.

The females’ colours are not so bright because they don’t need that. They use their pheromones and body language to communicate for mating. The male’s tails and fin are flowy and long.

Although you can use the colour and fin to differentiate the male from the female, it is not a reliable guide because, in some varieties of guppies, the females are also colourful with flowy and long tails. Looking at the other distinctive features will help you determine gender.

– The General Body Shape Is Different

The overall body of the male guppy is entirely different from the female guppy. The male guppies have overall smaller and thin bodies while the females are much bigger and heavy-looking bodies.

The females have a more rounded body. When the female guppy is pregnant, she looks boy, full and stuffed as she nears the time when she will give birth to the younger guppies.

– The Male’s Special Equipment

As the male guppy matures, his anal fin at the underbelly changes. The triangular shape of the fin changes. It becomes long and narrow and later develops to be a gonopodium. This special fin is used by the male guppy to deliver sperm to the female guppy.

Once he delivers the sperm, the female guppy can deliver cute, little fry once a month for seven months without coming in contact with another male guppy.

– The Gravid Spot

The female guppy’s most distinctive characteristic feature is her gravid spot. It is located on her underside close to her tail, it has a dark spot. The gravid spot becomes darker and bigger when she is pregnant and she’s approaching her delivery time.

It is sometimes possible to see the babies from within if the delivery time is very near. After delivering her babies, the gravid spot becomes light than it was but will get darker and bigger if she’s having another batch of babies.

With these features, you can easily differentiate the male guppy from the female guppy. As time goes on, it will get much easier to pinpoint a male from a female.

Can a Female Guppy get Pregnant without a Male Guppy?

No, a  female guppy can not get pregnant without a male. During mating, the male guppy delivers its sperm using a special fin known as the gonopodium into the female guppy. Once the sperm is delivered to the female guppy, she can store the sperm of the male guppy for almost seven months or possibly longer than that.

This sperm can fertilize the eggs once a month for as long as the sperm is there. This is what gives a lot of people the notion that the female guppy can give birth without mating with the male guppy. But in reality, a female guppy cannot give birth without mating with a male guppy.

How To Tell If Your Guppy Is Pregnant

After the male and female guppies mate, the female gets pregnant and gives birth in a month’s time. The only way to know if your guppy is pregnant is through the gravid spot. The gravid spot is located on the underside of the female guppy close to her tail and it is a dark spot.

When the female guppy is pregnant, the gravid spot becomes darker than it was and bigger. As she approaches her delivery day, the gravid spot becomes darker and bigger. When the delivery time is very near, you can see the babies from inside.

Once she has given birth to the frys, the gravid spot won’t be as dark as it was when she was pregnant. The only time it will get darker and bigger again is when she has another batch of little frys.


It is now clear that the myth that guppy fish can change gender, are hermaphrodites, or that they are all females is dispelled. Guppies in their fry stage might all look like females but from 4 weeks old, you can begin to see their difference.

Although some of the male guppies might develop their distinctive characteristics later than others, you can differentiate the female and male guppies either from how bright the male is from the female, their fins, or the presence of the male’s special equipment, and the gravid spot in the females. 

It’s okay for your guppies to look like females in their fry stage. As they grow you can pinpoint the females and the male’s using the different characteristics.

Written by Justin Michaels

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