Can Guppies Have Babies Without Males?

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Most aquarists prefer guppies to other fish species for a variety of reasons. These include ease of care, seemingly endless color and pattern variety, friendly attitude, and high adaptability. Many other guppy keepers, however, prioritize guppies for their unparalleled breeding capabilities.

Guppies are some of the most proficient breeders, given their ability to procreate monthly and produce dozens if not hundreds of fry every time. This brings us to this article’s main topic, which I noticed causes a lot of confusion on the internet.

Can guppies reproduce without males and, if so, how does that happen? Let’s shed a critical light on one of the guppies’ most famous and interesting behaviors that’s by no means unique.

Female Guppy Just Had Babies Without Male

You will see a lot of similar titles on various fish forums coming from people who have faced this unusual occurrence themselves. This problem is more obvious in female-only tanks, where some females can remain pregnant and produce offspring, despite not having access to any males for months.

This has led some to believe that guppies can either change sex or self-inseminate, casting even more confusion on the subject. The truth is both simpler and more intricate than that.

In reality, guppies can self-impregnate, not with their own sperm, but that of males with which the female has previously mated. Guppies belong to a category of animals called sperm hoarders. Other animals that fall into this category include the regular octopus, some fly species, the eastern diamondback rattlesnake, and even the domestic chicken.

The process is simple. The female mates with the male and stores its sperm inside the body for later use. The female’s body will feed the spermatozoa with sugar to keep it alive for longer periods of time. This behavior can lead to unexpected pregnancies, as the female in question will produce offspring despite not having access to its male counterparts for a long time.

In the case of guppies, this can lead to rather peculiar situations where you buy guppies for your female-only tank, and they continue to remain pregnant over months to come. No male is in the picture.

This usually happens because those guppy females have had access to males in the fish store where you bought them. They stored the sperm and are now using it to produce offspring every month. So, there you go, mystery solved.

As some interesting notes, researchers are currently still in awe over this behavior since it isn’t easily explainable from an evolutionary perspective. Or any perspective, for that matter.

On the one hand, it’s clear that female guppies store sperm to overcome the fact that male guppies have shorter lifespans, often dying a full year before females. This allows females to preserve the sperm of a genetically superior male even long after the male has died. On the other hand, it seems like female guppies will use their stored sperm to self-inseminate even if they have a lot of genetically fit male guppies around them.

They will still resort to their sperm reserves rather than getting new batches from the males around them. Why? Nobody really knows.

It’s also not clear whether the stored sperm degrades in quality, as some researchers believe. What’s clear is that the sperm is viable for insemination and will fertilize the female’s eggs multiple months after copulation. So, at the very least, not all of it dies over time.

How Long Can Female Guppies Store Sperm?

The limit appears to be 8 months, but that’s not always the case. Many female guppies will run dry after 3 months. The difference may come from how the female guppy has been environmentally engineered to behave.

Guppies coming from environments lacking in males may store sperm for longer periods, while those coming from male-rich areas don’t need to do that. This behavior shows one simple fact about the guppy world – females are those dictating the species’ sexual behavior.

Do Female Guppies Die After Giving Birth?

No, female guppies don’t die after giving birth unless facing pregnancy complications which are that frequent, to begin with. Guppies produce offspring every month pretty much for their entire lives, given optimal living conditions, stable water parameters, and adequate diets.

Seeing how guppies can live between 1.5 to 5 years in optimal conditions, you should expect many thousands of fry from one female only. The more you have, the more fry you should expect every month if you have a mixed guppy population. In the case of female-only tanks, the likelihood of guppy pregnancy is low, but never 0.

Unless you’ve bred your guppies yourself and kept the sexes separate, at which point the pregnancy chance really is 0.

How to Tell if Guppy Fish is Pregnant?

The female guppy will display an array of physical and psychological changes during pregnancy, most of these signs becoming more obvious 14 days into the pregnancy. Prior to this point, the pregnancy isn’t developed enough to influence the female in any meaningful way.

Some physical and behavioral changes to look out for include:

  • Inflated belly – The female’s belly will begin to swell gradually, becoming more visible after the 14-day mark. By the time the female guppy is ready to deliver, the belly will achieve an almost square shape towards the rear. Make sure you eliminate all other causes of belly inflation, which may include various diseases, overfeeding, and constipation.
  • Gravid spot – This is the go-to sign when assessing a female’s pregnancy state. The gravid spot manifests via a dark abdominal area and occurs as a result of the eggs developing in the womb. The eggs will hatch later on and the resulting fry will cause the gravid spot to appear larger and darker as they grow. By the time the labor sets in, the gravid spot will have become completely black and taken over almost the entire abdominal area.
  • Hiding behavior – Pregnant females will actively avoid males, especially the pushier ones, which male guppies are known for. You might see your female guppy retreating among plants, rocks, wood, and caves, especially towards the lower half of the tank. Since guppies are mid-to-top dwellers, this behavior should raise some suspicion. It’s important to detect these behavioral changes because females may hide because of male’s persistence to mate. If males are too pushy, females will experience stress and may become sick because of it.
  • Increased appetite – This behavior may be more difficult to notice, especially if you have many guppies and several of them may be pregnant. But, if you keep track of how much your guppies eat, you will notice changes in the feeding behavior of pregnant females. The female will eat more and fight with other males and females when feeding time comes. This isn’t evidence for pregnancy in and of itself, but it does suggest that.
  • Refusal to eat – If your healthy and active female refuses food with no explanation, that’s a sign that labor is about to set in. Female guppies will refuse food several hours before the labor.
  • Signs of labor – When the labor triggers, the female will stop swimming and eating and will sink near the substrate. You will see the female swimming slowly in one place and experiencing shakes and convulsions. This is an indicator that the fry are underway, and the delivery process may last for several hours, especially with more inexperienced female guppies.

Can Guppies Breed Other Fish?

Guppies cannot breed with other fish other than their species. But that won’t stop them from trying. Guppy males display an unusual sexual behavior in the sense that they tend to be always horny. This may cause them to attempt mating with similar-sized species like platies or mollies, despite the mix not being fruitful. The gonopodium doesn’t reason if you know what I mean.

Guppies can’t mate with fish outside their species because that’s how species work. A species defines a group of animals that can reproduce between themselves. If they cannot reproduce, they are not part of the same species.

What to Do with Baby Guppies?

The answer depends on your goals. I recommend moving them into a breeding tank soon after birth if you want to keep them. Or, better yet, move the laboring female in a separate environment. This will minimize the stress during delivery and eliminate the risks of the fry being eaten by the adults.

If instead, you plan on growing the fry for profit, you might need several tanks capable of housing multiple fish generations. Just make sure you equip them with all the necessary tools to provide the fry with optimal living conditions. You will need a heater, a decent filtering system, plants, tank decorations, etc.

You can also opt for selective breeding to obtain more unique specimens, either for personal use or selling. In this case, you will need several breeding tanks and a higher level of discipline and organizing. I would say you require around 5 breeding tanks, probably 7, to separate the different generations and keep track of the most desirable traits.

If you want nothing to do with guppy fry, simply allow them to be born in the main tank. Adult guppies will appreciate the food since they have no moral issues with cannibalism. If your guppies reproduce in a community tank, all fish species will work together to turn the fry into swift meals. Just let nature take its course.


Guppies are such prolific breeders that they can even breed without males around them. You obviously now know how that’s possible.

So, welcome to the family, I suppose. Now, go hit the fish forums and help some lost and confused guppy lovers out.

Updated: February 8, 2022
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