Top 25 Goldfish Facts That Might Surprise You (2024)

Featured Image - goldfish facts
Featured Image – goldfish facts
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: June 9, 2024
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Goldfish are a popular option for home aquariums, especially among children, but there is a considerable amount of misinformation about this species.

I remember when I bought my first goldfish several years ago, my local pet store told me I could keep three in a tiny bowl without a filter. Fortunately, I’d already done my research and knew this was bad advice.

If you’re new to keeping goldfish, it can be hard to differentiate between fact and myth regarding their care. That’s why I’ve compiled a list of my favorite goldfish facts, including some informative and fun ones!

Article Summary

  • Goldfish have a memory span of 3 to 6 months, contrary to the popular myth of a 3-second memory.
  • Goldfish have incredible records: a pet goldfish lived up to 44 years, far exceeding their average lifespan of 10-15 years, and some goldfish can grow up to 16 inches in length.
  • Goldfish have more fascinating facts: they can see more colors than humans as they possess four color receptors, and female goldfish can produce hundreds to a thousand offspring.

What Are Some Interesting Facts About Goldfish?

Goldfish in a Planted Tank
Goldfish in a Planted Tank

Goldfish are truly fascinating creatures, from their ability to recognize people to their fairly long memories! Below are some cool facts about goldfish that you might not know.

1. A Goldfish’s Memory Span Is Between 3 to 6 Months

You’ve probably heard the “fact” that a goldfish’s memory only lasts 3 seconds, but this is completely false. Goldfish can actually recall things for between 3 to 6 months, maybe longer, and can distinguish between different sounds, shapes, and colors.

There have been numerous studies to prove this, but in one such experiment, a group of researchers taught young goldfish to expect food when a certain sound was played. The fish were then released into the wild.

After 6 months, the researchers used a loudspeaker to play the sound again, and the majority of the goldfish swam over to the sound to get fed!

2. A School of Goldfish Is Called a “Troubling”

Rather than saying “ a school of goldfish”, you’d say “a troubling of goldfish”.

3. There Are More Than 200 Varieties of Goldfish

There are over 200 varieties of pet goldfish due to selective breeding, including the popular oranda, ranchu, bubble-eye, fantail, black moor, comet, and common goldfish.

And Goldfish fall into four main groups, single-tailed, double-tailed, double-tailed with a dorsal fin, and double-tailed without a dorsal fin.

4. Goldfish Were Originally a Genetic Mutation

During the Song Dynasty in ancient China, people began breeding silver-colored Prussian carps, which eventually resulted in a color mutation of fish sporting yellow-orange scales. Yellow was named the imperial color and was only allowed to be kept by members of the royal family.

Personally, my favorite goldies are the yellow goldfish, orange goldfish, white goldfish, and the red and gold variety!

5. Goldfish Have Been Domesticated for Over 1,000 Years

Goldfish Swimming Upwards
Goldfish Swimming Upwards

Goldfish have been selectively bred and kept as pets for over 1,000 years – the first one was created in Imperial China from the crucian carp for its orange color.

During the Tang Dynasty, ornamental ponds soared in popularity, so the “orangey-golden” color mutation of the crucian carp was highly desired.

This resulted in more people selectively breeding the fish to single out its golden color, leading to creation of the goldfish we know today.

6. The Oldest Goldfish In the World Was 44 Years Old

The oldest recorded pet goldfish, George, lived for a whopping 44 years. From 1974 to 2019, he belonged to Keith Allies from the UK. The average goldfish can live for between 10 to 15 years, but some species like the common goldfish live a very long life of up to 30-40 years.

With good care, maybe your goldfish can have a long life like George did!


There are many factors that can affect a goldfish’s lifespan, but some of the most common reasons why goldfish die prematurely are improper diet, inconsistent feeding, an unsuitable aquarium, and poor water quality. Large tanks or ornamental ponds are a must for these fish!

7. Goldfish Can Grow Over 12 Inches Long

Goldfish grow up to lengths of 12 inches, depending on the variety, the tank size, diet, and water conditions. Some adult fish can even reach lengths of 16 inches. The largest goldfish on record was 18.7 inches long and weighed a hefty 9 pounds.

Large goldfish like the comet goldfish belong in a big outdoor pond, water gardens, or an aquarium with a volume of at least 40 gallons.

8. Goldfish Don’t Have Stomachs

Goldfish Feeding
Goldfish Feeding

Goldfish don’t have a stomach like we do. Instead, they digest food and extract nutrients from it as it passes through their intestines. Feeding time for goldfish should be broken up into small but frequent sessions over the course of the day. Overfeeding your goldfish can cause them to get constipated.

9. Goldfish Don’t Have Eyelids

Like most fish, goldfish don’t have eyelids, so they can’t close their eyes even when they sleep.

10. Goldfish Are Omnivores

Goldies are omnivores as they eat both meat-based foods and plant matter. As many goldfish owners will tell you, goldies are not picky eaters. They’ll eat worms, algae, crustaceans – just about everything, including aquatic live plants!

A goldfish’s natural diet includes plants, algae, small crustaceans, worms, snails, insect larvae, and sometimes small fish. In the home aquarium, you should try and replicate this by feeding them high-quality fish flakes/pellets, live food like daphnia and brine shrimp, and fruits or veggies such as peas, apple, cucumber, and kale.

Personally, my goldies eat plants (unfortunately!), bloodworms, and goldfish granule fish food, shelled peas, spinach, banana, and grapes on a regular basis.

11. Goldfish Can See More Colors Than Humans

Goldfish can see in both ultraviolet and infrared light, whereas the human eye can only see visible light.

Goldies have four color receptors in their eyes, unlike humans who only have three. This means they can see blue, red, green, and ultraviolet!

12. Goldfish Come In All Shapes, Sizes, and Colors

Goldies come in a wide variety of shapes, sizes, scale types, and colors, such as black, white, orange, red, yellow, gray, and brown. The most common variety is shiny orange, followed by red and white.

13. There Are 3 Goldfish Scale Types

Goldfish Scales
Goldfish Scales

Goldfish come in 3 scale types: matt, nacreous, and metallic scales.

14. Goldfish Are Messy

Compared to other fish, goldies are incredibly messy – they produce a lot of waste and have untidy feeding habits. That’s why goldfish need a powerful aquarium filter, large tank setup, and frequent tank maintenance to keep them and their aquarium healthy.

15. Goldfish Are Considered An Invasive Pest in the USA

Goldfish are an invasive species in many parts of the USA, especially in North America. They negatively impact biodiversity and the aquatic ecosystem as they primarily feed on fish eggs and live plants.

As members of the minnow and carp family, goldies also lower the clarity of the water due to their feeding antics, which decreases the amount of sunlight that penetrates the water. This affects the growth of aquatic plants and results in habitat loss for other species.

16. The Scientific Name for Goldfish Is Carassius Auratus

The goldfish’s scientific name is Carassius auratus, but goldfish is by far the most common name for this domesticated carp!

17. Goldfish Can Survive In Low Temperatures

Goldfish, especially common-type species, can live in a very cold water temperature – as cool as 60 ˚F. However, in temperatures, this low, the fish’s metabolism will considerably slow down. You can get a heater to help you maintain a consistent temperature.


Warmer temperatures of between 68° to 74° F are ideal for most goldfish.

18. Goldfish and Koi Are Not the Same Species

Despite both being members of the carp family, goldfish and koi are separate species. They can be cross-bred, but the offspring will be infertile.

19. Female Goldfish Produce a Lot of Offspring

Female and male goldfish breed once they are around 8 months of age. Females carrying eggs can lay between a few hundred to 1,000 at a time. That’s a lot of babies!

20. Goldfish Can Be Housed with Some Species of Tropical Fish

A common misconception is that goldfish and tropical species can’t live with one another, but this is actually untrue! Although technically cold water fish, goldfish can live in a wide range of temperatures, so some tropical species that require similar conditions and habitats can be great goldfish tankmates. There are even some aquarists who successfully keep goldfish and betta together.

21. Goldfish Change Color Depending on the Light

Fantail Goldfish
Fantail Goldfish

Goldies produce pigment that reacts to light, allowing them to change color depending on the environment.

For instance, after turning on your aquarium lights in the morning, you might notice your goldie’s color is darker than normal. There are also cases where goldfish scales become black or become white due to ammonia poisoning which can be lethal to goldfish.

22. Goldfish Used to Be Traditional Anniversary Gifts

It was traditional for men to give their wife a goldfish on their 1-year wedding anniversary in Southern Europe during the early 17th century.

Goldfish symbolized fortune and good luck, so being given one as a gift was meant to signal a prosperous future.

23. Touching a Goldfish Can Put Their Health At Risk

It’s tempting to pet a goldfish due to their friendly appearance, but doing so can rub off the fish’s slime coat.

A slime coat is a mucus layer on a fish’s body that is used for protection from parasites and infections.

24. Do Goldfish Recognize Their Owners?

Yes, goldfish do recognize their owners! Not only can these fish recognize the person that frequently feeds them, but they can also distinguish between people.

My goldies act skittish and nervous whenever another member of my household feeds them. However, it’s a different story when I walk past my goldfish tank – they immediately rush over to greet me and beg for a snack!

25. Do Goldfish Need a Light At Night?

Goldfish in a Lighted Tank
Goldfish in a Lighted Tank

While goldfish do need around 12 hours of light per day, they also need a minimum of 8 hours of darkness, so a light at night isn’t necessary. In fact, subjecting your fish to more than 12 hours of light can lead to stress and poor health.

Final Thoughts

I hope I helped you discover some fun facts about goldfish and learned a little more about this beautiful fish in the process. Do you have any cool goldfish facts of your own?

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