Can Guppies Change Gender?

And according to the latest studies, guppies are not capable of changing their gender.

Every now and then some breeders claim that their male guppy suddenly became a female and even bore some baby guppies! Online forums as well as breeding communities are rife with such anecdotes.

That’s why we often hear the question; can guppies change gender?

In this article, we’ll explore this phenomenon in deep detail. Also, we’ll shed some light on the main reasons why some fish, that are similar to guppies, change their genders.

So, Can Guppies Change Gender, if Needed?

Many of the fish that change their genders are of the livebearer variety. These are the fish that keep the fertilized eggs inside their bellies, and as the baby fish grow to a viable size, the fish ‘gives birth’ to a bunch of fry.

Among the popular fish that exhibit this behavior, which is scientifically known as protogyny, are the Poeciliidae aquarium fish. This includes guppies, platies, mollies, and swordtails.

There are individual accounts of male guppies getting pregnant, or female ones acting like males. However, there’s no scientific proof that demonstrates these events. Many livebearers do change their genders, but this was never documented for guppies.

Silver and Green Fancy Guppy

Why Do Fish Change Their Gender?

Typically, fish have clear genders that they have from birth to full maturity all the way to their senior years. Courtship often works in the simple way of the animal kingdom, where males try to get the attention of females, then start a family.

There are some extremely interesting exceptions to that rule though. Around 500 fish species have the capability of changing their gender if needed.

The need for a gender change often occurs in extreme environmental situations. Problematic circumstances like having a scarcity of males or females often drive a sex transformation to rebalance the deficit.

Another group of fish exhibits hermaphrodite behavior in the face of danger or duress. These fish have both male and female organs, and they can easily self-fertilize if the need arises. This often happens when there’s a predator in the vicinity, or the fish finds itself completely alone.

The consistent perpetuation of a species is a powerful instinct. And it seems to surpass the rudimentaries of biology.

Can a Female Guppy Turn Into a Male?

This curious phenomenon of a female fish becoming a male is often seen in killifish, parrotfish, and kobudai. These tiny little fish are native to the tropics of Africa, and they live in both salt and freshwater. They’re highly adaptable in their sexual behavior as well.

A female killifish, which has plenty in common with guppies, often lays its eggs in its full female forms. Then, it shortly transforms itself into a male killifish and fertilizes the eggs. This is often observed in dire conditions like droughts or an abundance of predators.

Some breeders mentioned that they saw their female guppies go through a similar process. But that claim was never substantiated.

Can Male Guppies Get Pregnant?

Some fish are protandrous sequential hermaphrodites, which means that the males can become females and even get pregnant. Examples include Australian barramundi, black porgy, and gilthead seabream.

Clownfish are also known for their protandrous sequential hermaphrodites’ characteristics. These fish are often bred in limited populations, so there’s a high possibility that a few males find themselves without a female.

A male clownfish would opt for becoming a female when its mate passes on. There are some more conditions though. The breeders of the group are usually the largest male and the largest female, so there’s some selection here as well.

Male guppies are rarely claimed to go through that role reversal, even in anecdotal evidence.

What Fish Can Change Gender?

Hermaphroditism is documented in about 500 different fish species worldwide. The harsh living conditions, paired with the unique biological makeup of fish allow them to perform gender changes. This is often triggered by duress.

Three types of gender changes are known to us:

  • Protogynous sequential hermaphrodites: Fish that change from females to males, like kobudai fish.
  • Protandrous sequential hermaphrodites: Fish that change from males to females, like clownfish.
  • Bidirectional hermaphrodites: Fish that change from male to female, or vice versa, then back again. Examples include coral gobies.
  • Embryonic sex change: This is where baby fish change gender as a result of water pollutants.

The gender changes are controlled by a set of specialized hormones and enzymes. Certain environmental effects often trigger a chain reaction of physiological and biochemical changes. The transformation takes around 8 days to become complete and effective.

It’s worth noting that the amount of fish that possess these sequential hermaphroditic capabilities is tiny compared to the total number of fish species. It’s 500 to 32,000, which is about 1.6%, and the Guppies aren’t within that group.

At What Age Can You Tell the Gender of Guppies?

Baby guppies are quite identical, to the point that it’s almost impossible to identify the males from the females. It takes around 4 weeks for the gender differentiators to start appearing.

Here’s the easiest way to tell them apart.

  1. Size matters in gender determination! Female guppies are typically larger than males. The differences become clearer as they reach adulthood, where the females become 2 inches long, while the males barely reach 1.5 inches.
  2. Males are usually much more colorful than females. Also, their fins are more developed and rather pointed.
  3. Male guppies have a gonopodium beside their anal fin. This is their reproductive organ, and it’s how they carry their sperm to the females’ gravid spot.
  4. The gravid spot is a strong determinant of the female guppies. It’s a tiny dark spot in their lower abdomen where they’d later carry their baby guppies.

In Conclusion

Fish changing their genders isn’t an odd phenomenon and it’s widely documented in various marine studies. However, only a minute number of species can do that.

Male and female guppies have rather distinct appearances, but they’re not drastically different. It’s easy to see how mix-ups can happen with an extra-large male guppy, a brightly colored female guppy, or one with unusually structured fins.

In all these cases, breeders might assume a different gender wrongfully, and then assume that their guppies can change their gender.