How Big do Female Guppies Get?

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Females guppies tend to grow to around 1.8-2 inches long, and usually grow bigger and faster than males. When pregnant, female guppies develop a huge belly, making the size difference more significant. There are multiple factors that affect the growth of female guppies such as temperature, stress, food, and water quality.

There are other specific differences between guppy males and females. The most notable ones have to be the males’ coloring since males are more colorful than females, and the females’ bigger sizes.

Guppy males tend to have slightly more slender bodies, while females are bulkier and bigger overall. But why is that, and what does that tell us about guppies?

Let’s see what we can find out!

Why do Females Grow Bigger Than Males?

Females are bigger than males in almost all fish species for a variety of reasons. Some include the need to protect the offspring. Fish aren’t particularly monogamous, which means there’s no male to fill the role of a protector. This meant that females had to grow bigger and stronger to deter males or predators from testing them.

Another aspect revolves around food distribution and pecking order. Guppy females have a strict pecking order, leading to them keeping a check on other females and males beneath them. This pecking order determines access to food and space, among other things.

Last, but not least, females need to be larger to chase off males. This happens during the mating season, which is always since females get pregnant every month. Guppy females will mate with multiple males during that time until they get pregnant. The main problem is that the males will keep pushing even after the female has lost interest.

To counter that, the female will use its size and aggressive attitude to chase off males.

How Long it Takes for Female Guppy to Reach Full Size?

Typically, the female guppy will reach full size in approximately 6 months. This is generally speaking since the guppy’s growth, and growth rate will depend on a variety of factors. These include:

  • Water temperature – Guppies are most comfortable in temperatures between 72 to 82 °F since they are tropical fish. However, adults need lower temperatures than the fry. Adult guppies are fine with temperatures between 73 to 76 °F, but guppy fry require temperatures closer to 80-82 °F. These higher temperatures will boost their metabolism, accelerating their growth and increasing their comfort in the long run.
  • Dieting – While adult guppies and fry share similar food preferences, they also have some differences to discuss. Guppy fry need a fatter diet, consisting of more protein and fats. They will typically consume fat and protein levels that are unfit for adult guppies. Their diet will smoothen down with time and fall more in line with the adults.
  • A risk-free environment – Ideal temperature parameters will influence the fry’s growth significantly. It will also help to have the guppy fry in a tank of their own. The lack of predators or larger tank mates stressing them out may impact their growth along the way.

Guppies will reach their mature size within the first 6 months of their lives if all’s well.

Do Female Guppies Grow Faster Than Males?

Yes, females tend to grow slightly faster and bigger than males. One of the key factors influencing their growth rate, however, is access to quality food. The more diverse the diet, the faster the guppy will grow and mature sexually.

A warm and stable environment with an abundance of food will allow guppies to mature faster. This is a great aspect to remember if you’re planning for selective breeding.

How Big Does a Guppy Have to be to Have Babies?

It’s not necessarily about the guppy’s size but its sexual maturity. Female guppies mature later than the males. Male guppies will become sexually viable at around 2 months old, generally sooner than that.

Females, on the other hand, need around 2.5 to 5 months to reach the same stage. So, the answer is that it varies. When producing their first fry, some females will be significantly smaller than others, which means that body size isn’t really a reliable indicator.

If you want your guppies to mature faster and reproduce sooner, provide them with a warmer habitat, a varied diet, and optimal living conditions. Just know that guppy females that breed early may only deliver several fry. Guppy females can produce between 2 to 200 fry, with the lower end being more prevalent for younger females.

Are Baby Guppies Same Size at Birth?

Yes, they typically are the same size upon birth. You will also be unable to differentiate between the genders since all guppy fry looks the same. It’s only after they start growing that certain differences will become more visible.

Females will overtake males in terms of size, but males will develop more impressive colors and patterns with time. This is also why so many guppy keepers look for male-only tanks.


In essence, guppy males will grow between 0.6 to 1.4 inches as adults, while females will reach almost double that. Most female guppies revolve around 1.2 to 2.4 inches, making them way bigger and bulkier than the males.

The female will become even more impressive during the pregnancy phase when its belly expands considerably.

If you’re looking for bigger guppies for your tank, females are the ideal choice. If you want more color, choose males instead. I would recommend keeping a mixed aquarium with a healthy 1:3 male-to-female ratio.

Check my other articles for information on guppy diet, water parameters, guppy disease prevention, and treatment, or any other aspect you might find interesting.

Updated: December 9, 2021

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