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50+ Fun Facts About Goldfish You Probably Didn’t Know

Lindsey Stanton Profile Picture

By Lindsey Stanton

How’d you like to like to see my secret stash of mind-blowing fun facts about goldfish? Well, consider yourself very lucky, because today I’m going to pull back the curtain and share the absolute BEST ones with you.

Warning: You are not going to find anything about genetics or species history here.

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The 50+ Fun Facts About Goldfish:

1. The goldfish is the most popular aquarium fish in the world.


You heard it right, folks. In fact, they are one of the most popular pets EVER! Goldfish (along with dogs and budgies) have been kept as pets longer than any other animal.

Over 480 million goldfish are sold every year! That’s actually more than both dogs and cats combined. But that’s no surprise considering what great pets they make, right? Not to mention the price to take care of them is far less!

2. You can tell how old a goldfish is by its scales.

A tree and a goldfish don’t seem to have a whole lot in common. But get this: for every year of a goldie’s life, the fish develops a ring on its scales! Those rings are called circuli. Just count the number of rings (like you would on a tree stump) to determine the fish’s age.

Here’s the catch: You’d need a microscope to see them.

3. Goldfish actually see more colors than humans.


Guess what? Your eyes can only see combinations of three primary colors—red, yellow, and blue. Not a goldfish’s eyes! They can see FOUR different ones, which lets them see ultraviolet light.

This helps them see movement in the water and find food easier. But don’t feel too bad because a goldfish’s actual eyesight isn’t all that great. Their eyes are located on the sides of their heads, so they have a big blind spot right in front of their nose.

Plus, they can’t see very far. And certain breeds that have special eye modifications (like the Telescope or Bubble Eye) have even worse vision than normal.

4. It’s a myth that goldfish have a 3-second memory.

Some scientists in Israel trained their goldfish to come to a dinner bell sound. Then, they let them go into the sea. 5 months later they played the bell sound—and the fish all came back!

5. Goldfish are music experts (well, almost).


Japanese researchers used two pieces of classical music by different composers (Bach and Stravinsky) to test the goldfish’s knowledge of the arts. Half of the goldfish were trained to bite a red bead during Bach’s music—and the other half during Stravinsky’s music.

If they bit during their piece of music, they got food.

Granted, it took 100 of these “music lessons” to get them to tell the difference. But come finals… 75% of the time they chose the right one!

6. Goldfish have a sixth sense.

You may have noticed a row of tiny dots down each side of your goldfish. That’s called the “lateral line.” It’s an organ that actually gives a goldfish the ability to feel pressure changes in the water like vibration and currents. What’s it like?

Well, the best we can compare it to is hearing, touch, balance, and sonar all in one. So yes, your goldfish DOES have superpowers

7. There are taste buds on a goldfish’s lips.

Goldfish don’t actually have taste buds on their tongues—instead, they’re located all over the lips inside and outside of the mouth. That’s why you see goldfish pecking at everything in the aquarium.

They want to tell how it tastes!

8. If you keep a goldfish in the dark it will turn white.


True story:

A “feeder fish” lived in a filter for 7 years to escape from the tank predators. When it came out—it had turned completely white! Why?

No light = no color. That’s because light helps the goldfish to produce pigment in their skin.

Read More: Goldfish Tank Light for Healthy Fish

9. A goldfish will eat any fish that fits in its mouth.

The motto of life for a goldfish is, “If it fits in the mouth and can be eaten, it’s food.” As gross as it sounds: that includes their own babies.

So if you keep goldfish with other fish or much smaller goldfish, you might find that one day they’re here and the next day, they’re gone.

Many fish die as a result of improper food and/or portion sizes, which can be easily prevented by proper education.

The Truth About Goldfish New Edition

That's why our best-selling book, The Truth About Goldfish, covers exactly what you can and can’t give your goldies when it comes to mealtime. It’s even got a section dedicated to keeping your pet fish alive and well-fed when you go on vacation!

10. A president kept pet goldfish.

Grover Cleveland imported fancy Japanese goldfish for his ponds. He owned HUNDREDS of them!

11. Male goldfish have breeding stars.


You might have noticed some white dots on your fish’s gill plates or fin rays. They’re rough like sandpaper.

Nobody knows for sure what they’re for – but some think they might be to impress females or even be used as weapons for spawning behavior. Once in a great while, a female has them.

(Read more about how to tell the gender of a goldfish).

12. Goldfish can recognize faces.

And not just faces, but also shapes, colors, and sounds! So good news—you’re not just a shapeless blob to your pet.

13. Goldfish can’t blink.

So don’t try to have a staring contest with it! They don’t have eyelids… so they don’t even close their eyes when they sleep.

14. The goldfish lives longer than any other domestic fish.


Pretty astounding, right? Most people think goldfish can’t make it very long and die quickly. But just how long do goldfish live? Well, the oldest goldfish (on record) made it into his mid 40’s.

Yours can too.

But here’s the catch—ONLY if it is well taken care of will it live a long time.

15. Giving a goldfish as a gift was a sign of friendship.

This used to be a practice in Asia. A husband would give his wife a goldfish as a present on their first anniversary! That is until goldfish got more common.

16. They (usually) get along fine with each other.

There are some exceptions to the rule – like if your tank is too small or it’s breeding season—but for the most part, they get along with each other just swimmingly.

Matching in size seems to help, too.

17. You can train them to do tricks.


Some people think goldfish aren’t very smart. But get this:

Using food as a reward, goldfish can learn to do all kinds of tricks! Pushing a ball through a hoop, playing soccer, and going through an obstacle course are just some of what they can learn!

18. It’s a rumor that goldfish are messier than other fish.

Goldfish DO excrete lots of ammonia into the water. And more than, say, tropical fish. But that’s because they’re so much bigger.

They don’t produce more waste than any other fish of the same size. And as scavengers they are constantly cleaning up tiny specs of algae and food.

19. Goldfish don’t have stomachs.

The goldfish may seem to be on the short end of the stick compared to, well, the cow (which has four stomachs!). Instead, they have one long intestine that does the job of digesting in different areas.

Want to know something else? Food moves through it—FAST.

20. Royalty is in the goldfish’s blood.


At one point in China’s past, only royalty could afford the luxury of pet goldfish. They were even used as bribes by courtiers! The yellow-colored ones were the most prized by them. So if you were a peasant… you were BANNED from owning a yellow goldfish.

See, yellow was the imperial color. And THAT is why we have so many orange-colored goldfish around today.

21. At night, goldfish DO go to sleep.

No, they don’t close their eyes (because they can’t!) while they rest. That’s why they appreciate having the lights off at night. Their coloring may fade during this time, too.

Learn more about how goldfish sleep.

22. Yuck! Goldfish will eat their own poop.

Gross, right? Well, goldfish digest things pretty quickly. (Sometimes a little TOO quickly.)

So every once in a while they eat their poop to get the nutrients they missed the first go around.

23. A school of goldfish is called a “troubling.”


There’s no leader as they swim. Here’s how they do it: When one veers off, the others follow.

Or if they don’t follow, the runaway comes back to join the crowd.

24. Some goldfish are born albino.

Just because a goldfish is all white does NOT make it albino. It will have pink pupils instead of black ones.

25. They have a longer attention span than people.

9 seconds is the average goldfish attention span. But yours is probably only 8.

Why? Maybe because your fish doesn’t have a cell phone.

26. The largest goldfish is the size of a cat.


The Guinness record for the world’s longest goldfish stands at 18.7 inches from nose to tail. That’s pretty big!

In fact, it’s bigger than the average cat size of 18 inches long (without the tail). An Oranda named Bruce used to hold it at 15 inches.

27. Breed a koi to a goldfish and their babies can’t have babies.

Yep, just like if you breed a horse to a donkey. The resulting mule (or fish) won’t be able to reproduce. In fact, you may have seen some of these new “black comet” goldfish on the market lately. Actually, if you look closer you’ll see small barbels (koi whiskers) on their mouths.

They’re hybrids too!

28. The goldfish is tougher than you’d think.

Temperatures in the 100’s F. Frigged winter ice. Toxic water. Yep, goldfish have been surprisingly able to tolerate all of that—and far more.

Granted, the fancier kinds are more delicate, but even some of them have made it through unbelievable conditions. And while it’s never a good idea to keep a goldfish in a bowl, varieties like the Common have been known to endure it (incredibly) for years.

29. A goldfish WILL eat itself to death.


Now don’t blame them…If you didn’t have a stomach, you’d have a hard time knowing when you were full too!

They have one mission in life: eat. And eat as much as possible.

Hint: something to remember during feeding time.

30. Goldfish have teeth in the back of their throats.


If a goldfish took a selfie, it would have a pretty gummy smile. That’s because they DO have teeth—flat ones, but in the back of their mouths.

Scientifically, they’re called pharyngeal (far-in-jee-uhl) teeth. Listen closely at mealtimes and you may hear crunching as they grind up their pellets!

31. There are more types of goldfish than any other species.

The Chinese have numbered over 300 different varieties of goldfish. It’s taken many years and lots of hardworking breeders to get as many kinds of goldfish as we have now. The US has only contributed one of them, though.

Which one?

The Comet goldfish.

32. During spawning a female goldfish can lay over 1,000 eggs at a time.


Think you have a big family? Well, imagine having over a thousand siblings. But usually, not all of them will hatch—some will be fertilized, some won’t be.

Or some will be eaten.

33. Goldfish make sounds.

You just can’t hear them. If that doesn’t shatter your perception of reality… I don’t know what will.

Researchers using special technology found that goldfish make squealing and grunting noises through their noses while eating and fighting.

34. The goldfish is actually a carp in disguise.

The carp is actually the great-great-granddaddy of the goldfish. How are they so different? It all comes down to one thing:

Selective breeding. It’s just only taken about 2,000 years of it.

35. Goldfish do have brains.


In fact—all living animals have brains. Contrary to popular belief, goldies also have good memories (NOT 3 seconds like the myth goes). And in case you were wondering…

Fish such as the Oranda or Lionhead don’t have brains on top of their heads.

Those are wens—fleshy growths of skin.

36. For up to 3 weeks they can survive without any food.

That’s a long time! See, goldfish (like carp) are great at storing fat for lean times.


Next time you go on vacation, don’t sweat about who’s going to feed the fish. They’ll be better off without food—especially because most pet sitters overfeed.

37. All goldfish have clear scales.

Betcha didn’t know that one! The skin UNDERNEATH the scales is what gives each goldfish its own unique color pattern. How shiny the fish is depends on the type of scales. And a goldfish’s scale type will never change no matter how old it gets.

Goldfish can have metallic scales (shiny)…

matte scales (not shiny)…

… or nacreous scales (mix of shiny and not shiny).

Black moors have matte scales. That’s why they look so “velvety.”

38. Goldfish don’t have tongues.


Instead, they have a little “bump” on the floor of their mouth that helps them eat. It can’t move around like a human tongue though.

(And it has no taste buds!)

39. Goldfish have a sense of smell.

Believe it or not, goldfish can smell. And they actually have a better sense of smell than humans. Look closely and you can see two little flaps above your fish’s mouth—these are the fish’s nostrils called “nares.” They use their smell to find food and other fish. Bad smells (like poisonous water) make them feel dizzy.

40. A goldfish can grow to the size of its tank.

You may have heard otherwise but it’s a MYTH that goldfish can’t stop growing in a small tank. They will often grow huge in a big tank. But they produce a hormone that regulates their growth when water changes are not done frequently.

(This is true in big tanks as well as small bowls.)

41. Got a laser pen? Your goldfish will chase it!


Yeah, it’s true! Maybe some hunting instincts at work. It’s REALLY fun to watch a large group of goldfish in a tank all go for it at once.

42. Goldfish can hear.

They hear vibrations with internal ears called “otolith.” They don’t hear as well as people though.

A word of caution: Tapping on the glass of the tank can stress them out.

43. There is no such thing as a pregnant goldfish.

To be pregnant an animal (or person) has to be carrying live young in its womb. A female goldfish may have eggs inside her. But she has to release her eggs into the water for them to get fertilized by a male goldfish. Then the eggs stay outside the fish’s body until they hatch.

44. Goldfish can’t live in bowls.


Putting a goldfish in a bowl for its home is a big no-no. They are chambers of DEATH for just about every fish that lives in them! How come? Lots of reasons. But the main one is their water turns toxic really fast.

45. The fins and scales of a goldfish can grow back.

All is not lost for the goldfish who has been injured! Given clean water (and some time) they can repair most damage pretty well.


They might not if the fins have been shredded all the way up to the base of the tail.

46. Entire lakes have been taken over by goldfish.

Some people (stupidly) released a few goldfish into a lake in Boulder, Colorado. It only took 3 years before there were thousands of them!

How did the story end? They eventually were eaten by herons and the lake was saved.

47. A goldfish will eat out of your hand.


It doesn’t take long for most goldfish to learn where the food comes from. With a little patience, you can have your goldfish trained to eat from your fingers at mealtime. They don’t bite either as they nibble.

Cute, right?

48. To clear its gills a goldfish “yawns” backward.

No, they don’t yawn the same way as people. But they DO take in water the opposite way to flush out their gills. It’s not because they’re sleepy!

49. Goldfish get bored.

Life in a glass container by yourself with nothing to do all day… sound like fun to you? Of course not.

Goldfish need amusement, too! Here’s a solution—in the wild goldfish are foragers. Giving them fibrous veggies to graze on during the day isn’t just good for their health, it’s enjoyable for them as well.

50. There are infinite color combinations in goldfish.


Like snowflakes, no two are the same. That’s part of what makes them so much fun! In 3 generations of goldfish breeding back to carp, the babies will lose all of their bright colors.

51. In the winter goldfish kept outside go into hibernation.

Their heart rate slows down and they stop eating. Then, they sleep. After winter is over, they come out of their long winter nap often ready to spawn!

What Do You Think?

Now I want to hear from you. What do you think of this list? Maybe I missed an interesting piece of information?

Either way, leave a comment below right now to let me know.

And before I forget… don’t forget to check out our book so you can become a goldfish expert!

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