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Goldfish are the most popular aquarium fish in the world. Every year, over 480 million are sold! To put that in perspective, more goldfish are sold than dogs and cats combined. However, more households own cats and dogs.
Even though goldfish are popular, many amateur aquarists don’t know much about them. In this article, we have 41 facts about goldfish that may surprise you.
The 17 Facts About Goldfish Anatomy
1. Goldfish have brains.
Many people do not think goldfish are very smart and assume that they do not have brains, but goldfish are pretty smart, which we discuss in more detail in the intelligence section.
2. Goldfish eyes can detect ultraviolet and infrared lights.
Human eyes have evolved to see red, yellow, and blue colors and a mixture of these colors. Goldfish are better at seeing a wider range of colors. They have the ability to detect ultraviolet and infrared lights. This allows them to see combinations of four different colors, not just the three our eyes can pick up.
A goldfish’s ability to detect this extra color allows it to see movement and find food a bit easier. However, goldfish don’t actually have good eyesight. Because their eyes are on the sides of their head, there is a blind spot in front of their face, and they cannot see very far.
3. Goldfish don’t have eyelids.
Goldfish do not have eyelids. They cannot blink, and they do not close their eyes to sleep. It may be best to turn the lights off at night so that the goldfish’s sleep is not disrupted.
4. Goldfish taste with their lips.
Have you ever noticed that your goldfish pecks at things within its aquarium? It does this because it wants to taste everything around it. Unlike us, goldfish do not have taste buds on their tongues. Instead, they have taste buds on their lips and on the inside and outside of the mouth.
5. Goldfish don’t have tongues.
Their taste buds are on their lips and mouth for a reason. Goldfish don’t have tongues. Instead, they have a bump on the mouth floor, but it doesn’t move like your tongue does.
6. Goldfish don’t have stomachs.
Nearly every animal has a stomach, but not a goldfish. Most fish only have a long intestine that digests food in different areas. This causes the food to move through the fish much faster than it would if it had a stomach.
7. Goldfish teeth are in the back of their throats.
If you look at your goldfish’s mouth, it looks as though it does not have teeth, but goldfish have flat teeth in the back of their mouth. They are called pharyngeal teeth, and goldfish are not the only species to have them. The teeth are used to crunch and grind the food before it goes into their long intestine.
8. Goldfish scales tell you the age of the goldfish.
Just as you can tell the age of a tree by looking at the tree rings, you can tell the age of a goldfish by looking at the scales. Every year, it grows rings on the scales called circuli. Although counting the scales may sound simple, you need a microscope.
9. Goldfish get their color from the sun.
Speaking of scales, goldfish get their color entirely from the sun or light. If you take the light source away from the fish, they will not be able to produce pigment, causing them to turn completely white. Goldfish species are incredibly colorful, and you will never find two goldfish with the same colorations and patterns.
10. Some goldfish can be albino.
You can distinguish a white goldfish from an albino goldfish by looking at its eyes. Albino goldfish have pink pupils, not black.
11. Goldfish scales are clear.
This fact will probably shock you quite a bit, but goldfish scales are clear. The skin underneath their scales is what makes them have color. Goldfish scales can be metallic, matte, or nacreous.
12. Goldfish can detect changes in pressure.
The five human senses are sight, sound, smell, taste, and touch. Goldfish have all of these senses, plus one more. They can detect changes in pressure, such as vibrations and currents, because of a lateral line, which is a tiny row of dots that runs down their side.
13. Goldfish make noises through their noses.
Goldfish make sounds, even if you can’t hear them. Using unique technology, researchers detected goldfish making noises through their noses. The noises were comparable to squeals or grunting, and they are most commonly heard during eating and fighting.
14. Tapping on the tank will stress your goldfish out.
Even though you cannot see their ears, goldfish have internal ears called otolith. It allows them to hear, though their sense of hearing is not as good as humans. Their ability to hear means tapping their tank will stress them out.
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15. Your goldfish can probably smell better than you.
Goldfish have an impressively developed sense of smell that is often considered better than the ability of humans. They smell through the flaps above their mouth. These flaps are the fish equivalent to nostrils, or more technically called nares. Bad smells can make your goldfish feel dizzy.
16. Goldfish grow to the size of its tank.
This is partially true since goldfish cannot continue to grow indefinitely. However, their growth is stunted when they live in cramped conditions, and one goldfish needs at least a 20-gallon tank to develop properly. You also need to change the water frequently. Goldfish produce a hormone responsible for regulating their growth. This hormone is released whenever the water is not changed frequently enough.
17. Their fins and scales can grow back.
If your goldfish has been injured, do not immediately panic. If you properly clean the tank, it should be able to grow back injured fins or scales. The only exception is if the fin has been completely removed.
The 4 Facts About Goldfish Reproduction
18. Males have white dots on their gill plates or fin rays.
If you look closely at a male goldfish, it will typically have white dots either on the gill plates or fin rays. These white dots are rough, like sandpaper. Experts are not sure what these white spots are for, but many predict that they’re used for impressing females for mating.
19. Goldfish lay 1,000 eggs at a time.
A female goldfish will lay at least 1,000 eggs at a time. However, not all of the eggs will hatch. Some are never fertilized, whereas others are eaten before they can hatch. Because there are so many eggs at one time, goldfish can reproduce quickly.
A couple of goldfish were released in a lake in Boulder, Colorado. It only took three years for the fish to overrun the lake. It wasn’t until herons ate the goldfish that the natural balance was restored.
20. Females don’t get “pregnant”.
Although female goldfish lay 1,000 eggs at a time, females cannot get pregnant. They never have live young inside them. Instead, a female goldfish releases her eggs before they’re ever fertilized. The eggs stay outside the mother’s body until they hatch.
21. You can breed a koi with a goldfish, but their offspring will be infertile.
It is entirely possible to breed a goldfish with a koi, but their offspring will be a mule, which is a fish that cannot reproduce. The black comet goldfish is just one example of a hybrid between goldfish and koi. You can see the koi heritage by looking at the small barbels on the goldfish’s mouth.
The 4 Facts About Goldfish Food Habits
22. Goldfish will eat other fish.
Even though you feed your goldfish little pellets or flakes, goldfish can eat other fish as long as they can fit in their mouth. Goldfish will eat just about anything that fits in their mouth, including their babies and poop. That is why you should not keep goldfish in an aquarium with much smaller breeds.
23. Goldfish can and will eat themselves to death.
Goldfish don’t have a stomach, making it difficult to know when they are full. This causes many goldfish to eat themselves to death since the their purpose in life is to eat. Monitor how much you feed your goldfish during feeding time for this reason.
24. Goldfish can live without food for up to 3 weeks.
Even though goldfish are constantly hunting for food, they can live for up to 3 weeks without any snacks. That’s because goldfish store fat for lean times. So, you don’t have to hire a pet sitter whenever you go out of town for the weekend.
25. You can feed your goldfish out of your hand.
Goldfish can recognize faces (more on this later), which allows them to know you are their food provider. You can feed them out of your hand if you are willing to be patient and train them not to be afraid of your hand.
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The 6 Facts About Goldfish Intelligence
26. Goldfish have a 5-month memory.
One of the most common misconceptions about goldfish is that they only have a 3-second memory. This is simply not true. Studies have suggested that goldfish have a memory of 5 months. Scientists from Israel discovered this by training goldfish to come to the sound of a dinner bell.
27. Your goldfish has a longer attention span than you.
Humans have an average attention span of 8 seconds, but goldfish have an attention span of 9 seconds on average. This means your goldfish is better at focusing than you are.
28. Goldfish can do tricks.
Goldfish are so bright that you can train them to do tricks. Using food as positive reinforcement, you can teach goldfish to push a ball through a hoop or an obstacle course. You can even teach goldfish to chase laser pens. It is believed that goldfish chase laser pens as a response to their hunting instincts. You can also make an entire school chase a single laser pen.
29. Your goldfish probably recognizes you.
Goldfish have the ability to recognize faces, shapes, colors, and sounds. Your goldfish probably recognizes you and knows you as its feeder.
30. Goldfish can recognize different music and composers.
Goldfish can learn to recognize different music and composers. Japanese researchers trained goldfish to recognize music from Bach and Stravinsky. Half of the goldfish bit a red bead whenever Bach played, while the other half bit when Stravinsky played.
It should be mentioned that a goldfish took about 100 lessons to start recognizing the difference between the music. After the lessons, about 75% of the goldfish consistently picked the right composer.
31. Goldfish get bored.
Wouldn’t you get bored if you lived inside a tank? To amuse your goldfish, put fibrous veggies inside the tank for them to forage on throughout the day.
The 2 Facts About Goldfish Legend, Lore, and Culture
32. Goldfish were a sign of friendship in Asia.
Before goldfish became really popular around the globe, they were a sign of friendship in Asia. Giving a goldfish to someone else meant that you viewed them as a friend. Because of this practice, it was customary for husbands to give their wives a goldfish for their first anniversary present.
33. Goldfish were once a sign of luxury and royalty.
Way back in China’s past, goldfish were so rare that only royalty could afford them. Yellow goldfish were the favorite among royalty because yellow was the Imperial color. Yellow goldfish were so rare that they were banned from being owned by the peasants.
The 8 Other Fun Goldfish Facts
34. A school of goldfish is called a troubling.
Troublings are a little different from other schools of fish because there is no leader. Whenever one fish swims in a different direction, the entire troubling follows, or the lone fish will swim back to the group.
35. President Grover Cleveland loved goldfish.
Many animals have called the White House home. For Grover Cleveland, his pet of choice was a Japanese goldfish. President Cleveland didn’t just have a couple of fish, though. He had hundreds!
36. Goldfish have the most varieties than any other species.
To date, there are over 300 varieties of goldfish. Breeders have created this many varieties over thousands of years.
Through thousands of years of selective breeding, the goldfish descended from the carp. It may be helpful to think of the carp as the great, great grandfather of the goldfish.
38. The largest goldfish was 18.7 inches long.
When kept in a small bowl, goldfish will stay small, but they can grow really big if taken care of properly. The largest goldfish was 18.7 inches long, the average size of a cat, not including the tail. Imagine keeping that big boy as a pet!
39. Goldfish can live to be 40 years old.
Most people have goldfish that die rather quickly. When taken care of properly, goldfish can live to be over 40 years old, making them the longest-living domestic fish. Fish that do not live long die early because they were not properly cared for.
40. Goldfish can withstand a lot.
Part of the reason that goldfish can live so long is that they can withstand a lot. For example, they can live in temperatures as high as 100 degrees Fahrenheit, winter ice, or toxic water. Some goldfish have been known to live a long life even in a fishbowl, which is typically considered a lousy environment for goldfish.
41. Goldfish can hibernate.
If you keep your goldfish outside during the winter, it will hibernate. This involves the goldfish slowing down its heart rate and stopping eating before going to sleep. After the winter ends, the goldfish will be ready to spawn.
Conclusion
Who knew there were so many interesting facts about goldfish? For such small fish, they are fascinating creatures. Did you know any of these facts? Let us know in the comments!
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Featured Image Credit: dien, Shutterstock
