Are Guppies Hermaphrodites?

I see this question popping a lot when it comes to guppy breeding and sex. And, if you’ve hit the forums to find a relevant answer, you probably already regret the time you’ve wasted collecting all that contradictory information. So, let me help you out.

Before determining whether guppies are hermaphrodites or not, let’s have a look at the term itself.

What are Hermaphrodites?

Hermaphrodites are creatures with both male and female genitalia. The topic is vast, so I will only present the essentials to help you understand the phenomenon better. Hermaphrodites fall into 2 distinct categories (by one metric; there are multiple other metrics, leading to several other categories):

  1. Abnormal hermaphrodites – Only one pair of sexual organs are functional. The other pair is non-functional, resulting from genetic errors at birth. As a result, you either get a male with extra non-functional female organs or a female with extra non-functional male organs.
  2. Normal hermaphrodites – These are animals born with male and female functional organs. Some of them are born either male or female and become hermaphrodites under certain circumstances. The difference between normal and abnormal hermaphrodites is that the former can reproduce with any sex, as necessary, based on environmental conditions.

Some examples of normal hermaphrodites include most invertebrates and nematodes.

Can a Guppy be a Hermaphrodite?

The shortest answer you can get is no. You will, however, find a lot of conflicting information on the topic, most of it coming from uninformed individuals. I’ve encountered numerous voices stating that their guppies changed sex in adulthood, and I’ve thoroughly ignored them. That’s because anecdotal evidence is hardly evidence for anything in any field, particularly this one.

Let me explain.

Guppy males possess a gonopodium. This is the male sexual organ that the males will use to impregnate females. The gonopodium becomes visible in males during the juvenile stage when they are around 4 weeks old. But, and this are the magic words, ‘not always.’

Some guppy males will grow a visible gonopodium later on in life. They will also show duller, female-like colors. This can cause confusion among guppy owners, leading them to misgender their guppies.

This is literally where all the debate stems from – misgendering. These are simply cases of people mistaking undeveloped males for females, which appear to change their sex later on.

Can Female Guppies Have Babies Without Males?

Yes, but no. Don’t worry, this topic isn’t as confusing as the one regarding hermaphrodites, although it can seem like that. Generally speaking, guppies reproduce normally, but then you have the limit-situations, where male guppies are no longer part of the process.

In nature, guppy males can miss from the picture due to environmental conditions, predators, or other natural causes. In tanks, people may opt for female-only aquariums. Females will still get pregnant in both situations, despite not having access to males.

The phenomenon has to do with the female guppies’ ability to store the male’s sperm inside her body and use it monthly to self-impregnate. This is as far as guppies can go in terms of self-impregnation. It’s also the closest they will ever get to the notion of hermaphrodites.

It turns out that guppies can store the male’s sperm up to 10 or even 12 months. Since females live longer than males, some males can have offspring while dead for months. I could’ve used this subtitle for a greater clickbait-but-not-quite impact. “Dead guppy males can still make babies” has an interesting ring to it.

This phenomenon explains why newly purchased female guppies will produce offspring months on end, despite not having access to males during that time.

Can Guppy Fish Change Their Gender?

If they can, we haven’t seen it yet. There’s currently no scientific study showing that guppies can change their gender, outside anecdotical evidence, which you need to take with a lot of salt.

Even more interesting is that there are plenty of livebearing, and otherwise, fish that do change genders. Current science has identified little over 450 fish species that can change genders depending on specific environmental conditions. Here are 3 of them as references:

  • Clownfish – All clownfish are born as males. When the mating season begins and the males become sexually mature, the largest male of the group will turn into a female. If the group is larger, several males will become females with functional female organs. If something happens leading to the death of the females, other males will take on their role and change their gender. This way, the group will always remain balanced, no matter what happens with one gender.
  • Lyretail Coralfish – This species is the exact opposite of the clownfish. All individuals are born females this time, with one of them taking a male role down the line. The same events unfold as with the clownfish. If the male(s) die, another female will take its place.
  • Spined Loach – Most species of Spined Loach reproduce traditionally but can also change their sex under specific circumstances. In some species, the female will take on a male role, while in others, it’s the other way around.

The phenomenon of sex-changing in fish is way more colorful than this. The belted sandfish can change its sex almost immediately depending on the group’s needs. The chalk bass takes this ability to the next level, changing its sex 20 times per day whenever the group dynamic varies. It’s literally no big deal.


To settle things once and for all – there is no scientific evidence that guppies are or can be hermaphrodites or that they change their sex. So far, we only have circumstantial evidence of people claiming that their guppies have changed their sex. These are most likely cases of misidentification, leading people to mistake undeveloped males for females.

So, if you ever see your guppy females mating between them, one or more of them are impostors. Also, as I’ve already explained, females don’t need males to produce offspring, at least not for each pregnancy.

Until proven otherwise, guppies display traditional sexes and reproduce normally.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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