Guppy Fish Growth Stages

Guppy fish have short lifespans. Thus, they get big very quickly. What are the different growth stages of guppy fish? Here’s an overview and what to expect at each of the different guppy fish growth stages.

Guppy Fish Growth Stages - Birth to 6 Months to Adult
Guppy Fish Growth Stages – Birth to 6 Months and Beyond

Female guppies can grow up to 2 inches (5 cm), while male guppies up to 1.5 inches (3.8 cm) in size. Most of your guppies will be at full size in about 5-6 months with proper care and feeding.

How Big Do Guppies Get?

Guppies are livebearers which means that they give birth to live fry (baby guppies). They do not lay eggs. Males mate with females and the baby guppies develop within the mother’s body for 30 days before being born.


The baby guppies (fry) know how to swim at birth and seek hiding places soon after. Most of the time they are born deformed but straighten out within a few hours and are able to feed.

They are small; about 1/4 inch in length so they have to hide or be protected (by owners) as adult guppies can and will eat their young. To save the young, you can separate pregnant females from the main community or fill your aquarium with live plants for the fry to hide to increase their chances of survival.

Baby guppies can eat the same food as adult guppies. Simply grind the food into smaller bits so that it can fit their mouths. Baby brine shrimp is a good source of protein for the young guppies. Hard-boiled egg yolk is also another safe choice.

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Exposure to light for about 16 hours a day can also help them grow. Yes, guppies do sleep so you should not leave the lights on forever. If you feed the baby fry multiple times a day then frequent water changes are required.


At 1 month, baby guppy fry will have developed into juvenile guppies. They start to develop some color and you can now tell which are female and which are male.

Females will be much larger than the males and their gravid spot is often already visible. Males develop brighter colors. Guppies in the juvenile stage grow to about 1/4 and 3/4 inches (1.2 to 2 cm) in length.

During the juvenile stage of your guppies growth, give them plenty of food and clean living space. High-quality flakes, blood worms, spirulina, and brine shrimp are good options.

Young Adult

At around 2 months, most guppies are able to reproduce. You may want to separate males and females during this time if you do not want them mating. Doing this will also promote growth as they are not focused on mating but more on feeding.

At the young adult stage, lower fatty food intake and give them more protein and veggies. Yes, guppies can eat vegetables. Plankton pallets and spirulina help them develop more striking colors. Baby brine shrimp should still remain part of their diet.

Adult Guppy

Guppies reach the adult stage at around 6 months after birth. Growth stops or slows down significantly. However, the fins and tails of some species of guppies can continue to grow longer.

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Continue to feed your guppies a variety of food to help them maintain good health and their color. A flake-based feed high in protein is good enough to do this. Avoid fatty food.

At around 1.5 to 2 years of age, adult guppies become infertile and are not able to reproduce. The average guppy lifespan is 2-5 years.

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