Guppy Fry Growth Stages: A Full Guide With Pictures

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I remember how fascinated I was when I first saw guppy fry in my aquarium. I immediately wondered how long will it take for them to grow and how they were expected to appear during the following period. In other words, I wondered what the guppy fry growth stages are.

Stage 1 (days 1-30) – The fry are about 0.6cm in length and fully transparent.
Stage 2 (days 30-60) – The genital organs are seen and the fry is subtly colored.
Stage 3 (months 2-4) – The fry are sexually mature and present vibrant colors.
Stage 4 (months 4-6) – The guppies are considered adults and reproduce rapidly.

As we move forward, I will share some detailed pictures of the guppy fry growth stages. I will also discuss what you, as an aquarist, are expected to do in each stage. In the end, I will share an excellent video that shows how guppy fry grow, week by week.

Still curious? Feel free to check my complete guide on guppy fry. There, I discussed how to care for guppy fry, what they eat, how often to feed them, their growth stages, and much more.

What Are The Guppy Fry Growth Stages?

Guppies have a gestation period of 21 – 31 days.^[1] A guppy’s eggs hatch inside the mother’s body. By the time the female guppy pushes them out, the offspring are living, breathing fish.

They typically transition through the following stages on their journey to adulthood:

Stage 1: Fry (Days 1-30)

Guppies are just 0.6cm in length when the mother pushes them out.^[2] They are deformed at birth. But they unfold and straighten after a few hours.

They are more likely to survive than fish eggs because they can swim to safety, which is beneficial in tanks with predators. It is common practice to separate them from the parents. Adult guppies will gladly eat their offspring.

Despite their vulnerable state, they are not that difficult to care for because they eat the same food items as their older counterparts. However, you must crush the food into smaller pieces because their mouths are so small.

Additionally, their digestive cycles are just 30 minutes long. Therefore, you must feed them more frequently, about four to eight times a day. Baby guppies can eat as many as ten times a day. But food is just one aspect of the conditions they require to thrive.

They need a well-maintained tank with the same parameters adult guppies enjoy, not to mention 8 to 12 hours of daylight. You can perform small water changes every day to prevent toxins from spiking.

Stage 2: Juvenile (Days 30-60)

Guppy fry enter the juvenile stage after a month. Their size typically ranges from 1.2 cm to 2 cm. You can tell that they have left the first stage because you can identify their gender. You can see the gonopodium associated with the male guppies.^[3]

People expect the gravid spot to appear when a female guppy conceives. But, in truth, the gravid spot is always present. It simply becomes darker and more vivid during pregnancy.

If you check the area near the anal fin, you will see the gravid spot of a female guppy that has entered the juvenile stage:

Admittedly, the females will gain more color as well during this stage. But a male guppy is more colorful than its female counterpart. Therefore, you are more likely to notice the colors of a male guppy in the juvenile stage.

Experienced aquarists will encourage you to give baby guppies nutritious meals during this stage because of the impact it can have on their health and virility during adulthood. Try to include brine shrimp, spirulina, and bloodworms in their diet, along with high-quality flakes.

Stage 3: Teenage (Months 2-4)

Guppy fry are sexually mature at two months.^[4] The creatures are young adults at this point. Their colors will become more vibrant. The conditions to which you expose them at this stage will significantly impact their future.

You should maintain a clean tank. It isn’t enough to add a filter. Make a deliberate effort to remove any pollutants you encounter. That includes dead plants and animals.

You should also test the water routinely. You must keep the temperature, pH, and hardness within the appropriate range. Otherwise, you may reduce their lifespans.

Aim for these water parameters:

Temperature: 78-80 degrees F
pH: 6.8-7.6
Hardness: 8-12 dGH
Ammonia: 0 ppm
Nitrites: 0 ppm
Nitrates: <20 ppm

To measure the ammonia, nitrates, nitrites, and pH, I personally use the API Water Test Kit (link to Amazon). That is probably the most accurate I have found. It also lasts for about eight hundred measures, so it is definitely worth the investment.

If the water parameters are out of range, it is best to use water conditioners rather than frequent water changes, which may induce stress. If you don’t have one, make sure you check the Seachem Prime Conditioner (link to Amazon).

Give the teenage guppies ample proteins and greens to enhance their growth. Eliminate fatty food items. Even though fry and juvenile fish can eat them, fatty foods can ruin the health of adults and young adults.

For more information, feel free to check this article, where I discussed what guppy fry eat. I also gave instructions on feeding guppy fry and embedded some helpful Youtube videos.

The fish size may concern you, especially if some professional aquarists you consulted told you that guppies in the teenage stage were 2 inches long.^[5] But you don’t have to panic simply because your babies are smaller than two inches at this stage.

Like most fish, guppies grow at different rates. Some guppies will attain their full size in the first two months. In others, you have to wait for three, four, or even six months before the guppy offspring can reach their maximum length.

Some fish are smaller than the average size. They will remain small regardless of the food you feed them or the conditions of their aquarium. This shouldn’t concern, not when the guppies in question are healthy.

You should only act if a guppy’s small size is one negative symptom among many you’ve observed. You should apply this attitude to the sexual activities of the guppies.

Just because they are sexually mature at two months doesn’t mean they will breed immediately. In many cases, guppies start breeding after three or four months.

But some of them may avoid sexual activity for several months. Don’t forget: fish have individual personalities. They are not quite as predictable as people think.

That said, if you don’t want the guppies to breed, you should separate the male fish from the female guppies at this stage. Otherwise, they may overwhelm your aquarium with fry within a few months.

Stage 4: Adult (Months 4-6)

Guppies reach adulthood at six months. An adult guppy has an average size of 1.5 to 2 inches, which they attain within the first six months.

Guppies are unlikely to grow significantly beyond this stage. Their fins may grow longer, but the overall length of their bodies will remain largely unchanged. Any growth they undergo will be slow and minor.

Of course, you have exceptions to this rule. For instance, jumbo guppies have an average size of 2.5 to 3 inches.^[6]

If you did not separate the males from the females before, you should do so now. Otherwise, they will breed incessantly. Their lifespan will depend on their genetics, diet, and the conditions in the tank.

Guppies usually die within three years. However, they can live for five years under ideal circumstances. But they are only fertile for the first two years.^[7] Eventually; they will stop reproducing.

Don’t expect all the guppy fry to reach adulthood. A significant percentage will most likely die during the first few weeks. Some amateur aquarists will lose their entire population of baby guppies because they are still learning the ropes.

It is also worth noting that young guppies give birth to less than a dozen fry during their first pregnancy. A new aquarist is more likely to lose all those babies because they have less room for error.

Later on, when the guppies produce dozens, if not hundreds of babies, aquarists have more leeway. They can save some of the babies despite making mistakes.

If you found this article helpful, these may also interest you:

Pro tip: If your guppies breed frequently, you’ll need to know a little more about that process. Feel free to check my complete guide on pregnant guppies.

Conclusions

As guppy fry are born, they are entirely transparent. Some of you may even see the spine. As time passes, you’ll notice dots covering their backs and abdomens. Obviously, this also depends on the type of guppy you have, but most will follow this rule.

After a month, you’ll be able to see the reproductive organs. You’ll notice a slightly dark gravid spot in females, which is also seen if the fish isn’t pregnant. With males, you may see the gonopodium, although it is a bit more challenging.

After two months, their colors will become more vibrant. You first see this in females, and later on, in the males. Eventually, the males will become much more colorful than their female counterparts. Your fry are also sexually mature at this point.

After four to six months, your guppies are fully grown and considered adults. They are not expected to grow anymore. However, they will reproduce quickly at this stage, so you should separate the males from females if you wish to avoid more fry.