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Guppies are prolific breeders and don’t need any encouragement when it comes to increasing the population in your aquarium. So if you want to breed them you shouldn’t have any problems at all.
Guppies (Poecilia reticulata) are livebearing fish. Which means that the female gives birth to live young rather than depositing/scattering eggs. The male Guppy releases milt (semen) via his Gonopodium, which is his stick-like anal fin. The female draws this into her body and the reproduction process begins.
In their native habitat and in an aquarium setting Guppies will breed all year round. So if you have both male and female Guppies in your tank you’ll soon find that their number increases.
Even though your Guppies will breed without any help from you it’s worth knowing what to look out for when it comes to breeding.
Tip: Female Guppies can store sperm for up to a year after the initial mating. Which means that they can continue to produce fry even if all of the males have been removed from the tank.
Guppy Breeding Age
Because Guppies have a relatively short lifespan of 1-2 years on average they start breeding at an early age. They are ready to reproduce at between 1-3 months old, although 2-3 months old is more usual. And because they are likely to be at least this age when you buy them your Guppies are ready to get going as soon as you put them into your aquarium. In fact they may have already started breeding while they were in the store’s tank.
As with any livebearer that has been kept in a mixed sex tank it highly possible that the females you buy will already be pregnant. Some stores keep the males and females in separate tanks. But there’s still no guarantee that at least some of the females mated before being separated from the males. I had this experience with some of my Platy fish so it’s best to be prepared for some early new arrivals.
How Can You Tell A Male Guppy From A Female?
Gender differences between male and female Guppies are easy to spot once you know what to look for. So let’s have a look at the tell-tale signs that make it easy for you to determine the sex of your fish.
- Male Guppy – Male Guppies are smaller than the females. The average length for a male is 1.5 inches/3.81 cm. Their bodies are more slender than the females and are also more colourful. The male’s caudal fin (tail fin) is larger, more fan shaped and, just like its body, it’s more colourful than the female Guppy’s. The dorsal fin (top fin) is longer and more colourful too. The best tell-tale sign is the anal fin. In a male this fin is stick-like in shape and is called a Gonopodium. It’s used during mating to pass the sperm to the female.
- Female Guppy – Female Guppies are larger than the males. The average length for a female is 2 inches/5.08 cm. Their bodies are more rounded and generally less colourful than the male’s but this can depend on variety. The female Guppy also has a Gravid Spot (dark marking) at the rear of her abdomen near the anus. The female’s caudal fin (tail fin) is smaller and often less colourful too. The dorsal fin (top fin) is smaller than the males and less ‘flowing’. The best tell-tale sign is the anal fin. In a female this fin is triangular/fan shaped.
When it comes to breeding Guppies it’s important to be sure that you have both males and females from the very beginning. Fortunately it’s usually easy to tell them apart even when they are young.
Guppy Male To Female Ratio
For mating purposes the male to female ratio should be 1 male to every 3 females. Although a higher number of females to males is even better. The reason for this is that females can become exhausted by continual breeding/birthing. And having too many males and not enough females can lead to fighting between the male Guppies.
Female Guppies often die after having a batch/batches of fry. This is due to the stress caused by an almost continual mating cycle and also by bearing a large number of babies. By having lots of females and only a few males it will help to reduce the stress of reproduction on the females. It will give the female Guppies a chance to rest before breeding again.
So if you want your Guppies to breed successfully, with the minimum of female losses, keep far fewer males than females in your aquarium.
If you don’t want your Guppies to breed at all, then it’s best to only keep male Guppies. Not only are male Guppies smaller and more colourful than the females, you can at least guarantee that they’re not going to be pregnant already when you buy them.
Guppy Mating Behaviour
The Guppy mating ritual is fascinating to see. The male dances around the female, bending and twisting his body, and showing off his colourful, flowing fins. He works really hard to impress the female and to get her to accept his advances. If he is accepted he goes alongside the female and you may see him tapping her with his anal fin (Gonopodium) for a couple of seconds. If the female is still receptive to his advances he releases and passes a ‘packet’ of sperm for her to take in. The actual moment that this fertilization happens is so fast you’re unlikely to see it.
How Can You Tell If Your Guppy Is Pregnant?
When a female Guppy is pregnant you will notice a change in her Gravid Spot. The gravid spot is a dark/black area on the underside of the abdomen near the tail end of the fish. As the pregnancy advances, and the fry get bigger, the gravid spot becomes larger and darker. And the female’s tummy swells making her look plumper than usual.
As she nears the end of her pregnancy her tummy may change from being rounded to being squarer in shape. This change of shape is common in livebearers and is often referred to as ‘squaring-off’.
It’s sometimes possible to see the eyes of the developing fry as they near birthing time and push against the inner wall of the female’s abdomen.
All of these signs make it easy for you to tell if your Guppy is pregnant.
How Long Are Guppies Pregnant For?
The average gestation/pregnancy period for Guppy fry is between 21-30 days. It can vary a bit though depending on tank conditions and temperature, fish health/age and food quality. Nonetheless, you’re likely to find that your Guppies give birth regularly during the estimated time period. In fact it can be almost a monthly thing.
Knowing exactly when the birthing day will be can be difficult to judge. You’re highly unlikely to know the exact date of conception. Which means knowing which particular day the fry will be born on is unlikely too. But at least you won’t be surprised when you see the tiny fry swimming around the tank.
How Do Guppies Give Birth?
It’s likely that your pregnant female Guppy will find a quiet, secluded place in the tank to give birth. When the fry are born they drop down into the tank. If plants are close by they will rest in them for a while. If there are no plants the fry will rest amongst the substrate. Once rested they will be free-swimming. And it’s surprising how fast a new born Guppy can swim.
It can take a while for all the fry to be born. So the female Guppy may keep herself secluded/apart for quite some time. Once all the fry are born, and she feels ready, she will go back into the mainstream of the aquarium.
Tip: Some female Guppies die after giving birth to their first batch of fry. Others will go on to have many batches during their lifetime.
The YouTube Video link below is by The Dave. It’s a close up view of a Guppy giving birth which also shows you that sometimes things can go a little wrong. This video is definitely worth watching if you keep, or plan to keep/breed Guppies.
How Many Fry Do Guppies Have?
Although it can vary greatly, Guppies give birth to between 5-40 fry at a time. Sometimes it’s less and sometimes it’s considerably more. As with any livebearer each batch will produce a different number of fry from the last batch. Some of the fry will survive and others unfortunately won’t. I know that sounds a little sad but it’s just the way of things.
Nonetheless, Guppies are prolific breeders. So despite a few losses along the way you will find that you have plenty of healthy fry in no time at all.
Do Guppies Eat Their Fry?
Guppies will, and do, eat their own fry. Fry are often eaten by their own mother as soon as they are born. Some of the fry will be eaten by the other Guppies in the tank and often by any other fish that share the aquarium. The Guppy’s non-parental attitude does help to keep their numbers down and can help to prevent your tank from maxing out. But if you want to save as many fry as possible there are things you can do that will keep your losses to a minimum.
Read the next section for some helpful tips on saving Guppy fry.
How To Save Guppy Fry
There are several things you can do to help prevent your Guppy fry being eaten by the adults and/or tankmates. I’ve put together a few ideas that will help when it comes to saving your Guppy fry. They’re not complicated or expensive ideas. But they are a great help whether you want to keep the babies for yourself or you want to sell/swap them.
Here’s a few ideas to help you save as many Guppy fry as possible:
- Plants – use plants (live or fake) to create hiding places for the fry. Dense leafy plants/mosses and long rooted floating plants are all good choices for this.
- Tank Decorations – use tank decorations with tiny ‘hidey holes’ for the fry to shelter in. Cholla wood, often used in shrimp tanks, is one option. But any tank decoration that has holes too small for adult Guppies to get into will do the same job.
- Add A Breeder Box inside the tank to put the fry in until they are too big to be eaten. Guppy fry grow quickly so you won’t need to keep them in the breeder box for long. The size of the breeder box will dictate how long you can keep them in there for without stunting their growth. The bigger the box the longer they can stay in there. If you have larger fish in your aquarium/community tank that will still be able to eat them at this stage take a look at the next option below.
- Nursery Tank – Set up a cycled planted nursery tank ready for when your Guppies start breeding. You can put the pregnant females inside the nursery tank shortly before they are about to give birth. Then remove the females when they have finished birthing. Or you can use the nursery tank to grow-out fry before adding them to the main aquarium.
You also have the option of leaving things to nature and seeing how many Guppy fry you end up with over time. This option is often chosen by breeders because it’s usually the faster, stronger, healthier fry that survive. It’s also a good option if you don’t want to overpopulate your tank. Or you find it difficult to rehome the constant supply of babies.
Feeding Your Guppy Fry
Guppy fry are extremely small at approximately 6 mm/0.23 inches maximum at birth. So any foods you give them need to be tiny. For example, you can feed them powdered flake food, micro powdered fry food and also liquid fry food. There are other options too.
If you would like more information and some tips about what to feed your Guppies, both the adults and the fry, click on the link to read my article ‘What Do Guppies Eat?’.
