Guppies are Breeding Too Much – What Should You Do?

Guppies are well known for their high reproduction, which is why they’re also called the million fish. This species is well distributed among the expert and beginner fish keeper demographic. Many of us have guppies at home, mainly thanks to their vivid colors and dynamic behavior.

But when your guppies start mating uncontrollably and the population spikes, it becomes a real problem. Live-breeder species like guppies are extremely prolific, and the fry grow quickly.

It may sound like an exaggeration, but your aquarium might be overflowing with guppies in just a single day of mating. Keep in mind that one pregnant female can give birth to 50-60 fry at a time, and she can become pregnant again shortly after giving birth.

In this article, I’ll talk about breeding control methods for guppies. To maintain the population at an acceptable number, you’ll need to take a few severe measures.

Why Would You Suppress the Guppy Population?

Overstocking is a real problem when dealing with guppies. If the guppy population breaks loose, the fish will become progressively more stressed. There won’t be enough space for individual guppies to move around, which leads to stress. There’s also the problem of waste production, which will explode with so many fish in the tank.

Guppy overbreeding issues are all too common, especially for beginner fish keepers. Even people with a few years under their belts as fish keepers will sometimes have problems with overpopulation. Then, why does overbreeding occur? What can you do to stop it? More importantly, what will you do with the excessive guppy fry?

You see, guppies are an invasive species. Biologically speaking, invasive species have a low lifespan in the wild, so they’ve adapted toward extreme proliferation to address that low lifespan. Female guppies will give birth to a few dozen live-bearing fry at a time. Overpopulation quickly becomes a problem in closed spaces.

In the wild, overpopulation is rarely a problem because the swimming space is almost unlimited. Overstocking never occurs, and either way, there are natural predators that will hunt down guppies, preventing their population from growing in number.

Here’s what problems you can expect if you let your guppy population breed too much:

– Aquarium Overstocking

Overstocking is a no-brainer. A living space can only support a maximum number of living animals. The same applies to any herded animals, including sheep, horses, goats, and even fish in an aquarium. Depending on the size of an aquarium, the maximum overstocking limit is also higher.

But the million fish will quickly go above that limit if you don’t control their breeding. As more and more fry are born, waste production rises astronomically. The water cleanliness level reduces substantially, which is a direct cause of overstocking.

One personal disadvantage of overstocking is the visual impact. When an aquarium has an abundance of fish swimming around, it’s not as pleasant to look at. A rarefied aquarium with a decent number of fish looks more natural, right? But that’s far from the real issue at hand when it comes to overpopulation.

– Increased production of waste

This is a big one that shouldn’t be ignored. When an aquarium becomes overpopulated with guppies, the waste production of the fish grows exponentially. The water isn’t clean anymore, and this will make the fish sick. Why do you think all expert fish keepers recommend keeping the water clean at all times? Because the repercussions of not doing so are severe.

When an aquarium is overstocked and the fish produce too much waste, keeping the water clean becomes a hassle. You’ll need to perform water changes multiple times a day until it becomes too much of a time-waster. If you don’t change the water often enough, your fish will become sick and even die. It’s not a situation you want to deal with, I assume.

Even if you change the water regularly, all the accumulated waste harms your fish’s health. Imagine how you would feel if you were living in a filthy home with feces and urine all over the place. Yeah, living in that pigsty will ruin your health in time. The same goes for fish.

– Lower oxygen levels

Oxygen is limited in an aquarium. Fish need oxygen to live. Too many fish will lower the oxygen levels too much. See where this is going? If your tank is overpopulated, the oxygen levels will drop so much that some fish may even die.

At the very least, the fish will grow weak and anemic. They’ll be more vulnerable to diseases like fin rot, swollen gills, Velvet, Ick, and Protozoans. Clearly, you don’t want the oxygen levels in the aquarium to drop.

What Can You Do with Guppy Fry?

Your guppies have started breeding uncontrollably and you need to do something about it. That’s fine, but what’ll you do with all the fry? You can’t just kill them, right? Here’s what you can do with them:

  • Give them to friends – Who wouldn’t like receiving fish as a gift? If you know some of your friends are avid fish keepers, gift them a couple hundred fry. Even if they’ll use the fry as snacks for other carnivore fish, it’s not your problem. At least you’re dealing with the overpopulation problem in your tank.
  • Sell them – Everything can be sold on the internet, especially guppies. You could make a few bucks by selling the excess fry from your aquarium. I suggest separating the fry from their parents, raising them, and then selling them on online marketplaces like eBay.
  • Let them be – Do nothing and nature will deal with it for you. After being born, fry are at risk of being eaten by their parents and other guppies. If you don’t do something about it, the problem will disappear by itself. You shouldn’t feel bad about it because that’s nature for you.

There are quite a few things you can do with guppy fry, but they’re more of a hassle. I recommend focusing on the three solutions I proposed. They’re simple, accessible, and won’t take too much effort, especially the final solution.

How Do You Control Guppy Overpopulation?

Until now, we’ve talked about improvised solutions when overpopulation is already upon you. But you can also prevent it more intelligently. You don’t have to improvise on the spot when it’s already too late.

Do this:

– Separate males from females

Keep the guppy males and females separate and the risk of overpopulation goes to zero. There’s no better solution to overstocking issues. Avoid keeping a mixed-gender tank and all your problems are gone!

But hold on, it’s still not over. Perhaps some of the females you bought were already pregnant. Moreover, you could also misidentify the guppy genders when buying them. So, instead of buying an all-male or all-female population, you’ll buy mixed genders.

The best thing you can do in this case is to compromise and keep one male guppy to 2-3 females in your tank. The population will still increase but it won’t get out of hand any more. If you have no problem with additional fry appearing from time to time, then this solution is your best bet.

Still, if you want to keep all-male or all-female tanks, this is how you identify the genders more accurately:

  • Males have elongated anal fins
  • Females have rounded abdomens
  • Males are smaller compared to females
  • Females are less colorful and have smaller tail fins than males

This should help you avoid buying mixed genders from the fish shop. So, the overpopulation problem is a goner.

– Reduce the hiding places

You already know where this is going. Guppy fry need hiding places to escape their psychopathic-cannibalistic parents. If they don’t have enough hiding places, they’ll get eaten, and the overpopulation problem is solved just like that. At least, you’re not personally killing the fry.

Fry use plants, rocks, and other decorative elements in the aquarium to hide from guppy adults. Remove these elements from the tank to reduce the survival chances of guppy fry. The fewer hidings places, the fewer fry will survive the parental purge.

– Consider adding predator fish into the aquarium

Female betta fish are aggressive enough to eat the excess guppy fry in your aquarium. Just one female betta fish is enough for an aquarium, and your overpopulation problem should disappear in a few days. A word of warning, though – don’t put more than one female betta fish in the aquarium.

Betta fish are aggressive with one another, and they’ll likely pester each other to death. Instead of eating the fry, they’ll attack each other, and that’s not helpful at all. One female betta fish will take care of the excess fry and may even bother guppies enough, so they don’t mate as much.

Wrap Up

While guppy overpopulation is problematic enough, there’s no shortage of solutions to deal with it. Either you improvise and give away, sell, or indirectly kill the fry after being born, or you prevent overpopulation by dealing with the parents. You could separate the males from the females, reduce the number of females, or avoid mixed-gender tanks.

If you sell the excess fry on the internet, you’ll even make a profit. Turn the problem on its head and make it a fortunate encounter! Whichever solution you find preferable, I can answer any question down below, so feel free to leave a comment!

Guppies   Updated: September 16, 2022
avatar 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.
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