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July 26, 2026Sources cited
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Guppy

The guppy (*Poecilia reticulata*) is a small tropical freshwater fish in the family Poeciliidae.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

The guppy (*Poecilia reticulata*) is a small tropical freshwater fish in the family Poeciliidae. It is native to northeastern South America and nearby Caribbean islands, and it has been introduced widely around the world. Guppies are popular aquarium fish and are also used as model organisms in ecology, evolution, and behavioural research.

Taxonomy and naming

The guppy belongs to the family Poeciliidae and its scientific name is *Poecilia reticulata*. Common names include guppy, millionfish, and rainbow fish.

Distribution and habitat

Guppies are native to northeastern South America and nearby Caribbean islands, but they have been introduced far beyond their original range. They are among the most widely distributed tropical fish in the world.

They live in freshwater and brackish waters, especially warm streams, ponds, and shallow pools.

Biology and reproduction

Guppies are livebearers, meaning females give birth to free-swimming young called fry. Males are usually smaller and more colourful than females, and the species is known for its broad colour variation.

Adult guppies typically reach about 1–2 inches (2.5–5 cm) in length and have a lifespan of about 2–3 years.

Human use

Guppies are among the most popular freshwater aquarium fish because they are hardy, colourful, and easy to breed. They are common beginner aquarium fish.

Guppies are also used as model organisms in scientific studies of ecology, evolution, and behaviour. In some places, they have been introduced for mosquito control, as their diet includes small aquatic organisms and insect larvae.

Key facts

  • Guppies are small livebearing fish rather than egg-layers.
  • They are native to fresh and brackish waters in northeastern South America and the West Indies.
  • They have been introduced to many regions worldwide and are among the most widely distributed tropical fish.
  • Male guppies are typically smaller and more brightly coloured than females.
  • Guppies are common aquarium fish because they are hardy and easy to breed.
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Canadian context

Guppies are common in the Canadian aquarium trade and are familiar to many home aquarists in Canada. Canadian readers may also encounter guppies in discussions of invasive species, aquarium care, and freshwater fish biology.

Frequently asked questions

What is a guppy?
A guppy is a small tropical freshwater fish in the species *Poecilia reticulata*.
Where are guppies native to?
They are native to northeastern South America and nearby West Indies islands.
Do guppies lay eggs?
No. Guppies are livebearers and give birth to live young called fry.
Why are guppies popular in aquariums?
They are hardy, colourful, and easy to breed, which makes them common beginner aquarium fish.
Are guppies invasive?
In many places outside their native range, guppies are considered invasive because they can spread and affect local ecosystems.
How long do guppies live?
Most guppies live about two to three years, although lifespan can vary with care and conditions.

References

  1. Wikipediahttps://en.wikipedia.org/wiki/Guppy
    Supports: Scientific name, family, livebearing reproduction, native range, global distribution, research use
  2. Britannica Kidshttps://kids.britannica.com/students/article/guppy/274703
    Supports: Native range, family, scientific name, diet, aquarium popularity
  3. Britannica Kidshttps://kids.britannica.com/kids/article/guppy/601145
    Supports: Habitat, introduced range, invasive status, size, colouring, live birth
  4. PetMDhttps://www.petmd.com/fish/guppy-fish-care-sheet
    Supports: Native range, aquarium popularity, lifespan
  5. The Spruce Petshttps://www.thesprucepets.com/guppy-fish-species-profile-5078901
    Supports: Scientific name, lifespan, origin, common names, aquarium popularity, named after Robert John Lechmere Guppy
  6. Aquarium Co-Ophttps://www.aquariumcoop.com/blogs/aquarium/guppy-care-guide
    Supports: Popularity in aquarium hobby, livebearer description, mosquito control history
  7. WebMDhttps://www.webmd.com/pets/what-to-know-about-guppies
    Supports: Native range, invasive status outside native range