Goldfish Memory Span: How Long Is It? Interesting Facts to Know

Having the memory of a goldfish (Carassius auratus) is a comment typically used to represent the myth that goldfish only have 3-second memories. People typically use it when they walk into a room and forget why they were there, or when they forget to do something important.

In truth, goldfish have very good memories, remembering objects and their placement for several weeks and being able to use these objects for navigation and other purposes. There’s no real evidence of where the myth started, but it persists throughout the world, with some variance in exactly how short the fish’s memory is.

Not only do goldfish have better memories than we give them credit for, but they are also considered intelligent animals.

The 3-Second Myth

It is unclear where or how it started, but there is a prevailing myth that Goldfish have short memories. In some parts of the world, they claim it to be 10 seconds. In others, they say 2 seconds. And many claim it to be 3 seconds. So poor is the goldfish’s memory, apparently, that people are said to have the memory of a goldfish when they are extremely forgettable.

The Reality

While having the memory of a goldfish is meant to be a derogatory statement, the reality is that goldfish actually have good memories. They are also intelligent and they learn quickly, according to studies.

One study conducted at Oxford University trained a number of goldfish to swim just under 3 feet and then swim back. The fish received a food reward when they returned. During the training run, fish received a visual cue when they reached the end of the first leg of their journey. They would then turn back and swim to where they started.

Having set up visual markers every 2cm down the track, the researchers removed the visual cue. Even without a visual cue to turn back, 8 out of 9 fish turned back at the same distance and returned to their starting position to receive the reward. And when the background markers were changed, the fish still successfully completed the trial.

Many owners will recognize that fish know which side of a tank they typically get fed on, too. They will congregate in the same area, not only when it is time for food but generally throughout the day. Some will even learn to recognize the approach of their keepers and identify them as a food source. All of which points to a memory that is much longer than 3 seconds, and also points to levels of intelligence we don’t necessarily associate with fish.

The 5 Other Interesting Facts About Goldfish

Goldfish are fascinating creatures. As well as being more intelligent and having a better memory than most people think, below are other interesting facts about these little aquatic animals.

1. They Can Live 40 Years or More

Goldfish will generally live around 10 to 15 years when kept in a suitably sized tank and with adequate water quality. However, they can live much longer. One fish named Tish lived to be 43 years of age when he died in 1999. For some time, Tish shared his bowl with another Goldfish, Tosh, who lived to be 19 years of age.

2. Goldfish Can Grow Over a Foot Long

As well as shortening their lifespan, keeping a goldfish in poor water conditions can also stunt its growth, but with good water quality, the right genetics, unlimited food, and unlimited space, one can grow to be well over a foot long. The world’s largest goldfish was caught at a fishery in France and weighed a whopping 67 pounds, 4 ounces. That’s about the same weight as an adult Labrador.

3. They Can See Ultraviolet Light

Goldfish have four types of cone cells in the retina, giving them tetrachromatic color vision. This includes a cone cell which can detect ultraviolet light. At least 16 other species of fish have this trait. Goldfish, in comparison with other fish, have few of these ultraviolet receptors.

4. They Can Lay Thousands of Eggs at a Time

Although only a small portion of them will be fertilized, a single female goldfish can lay thousands of eggs at a time. However, it is more common for them to lay hundreds of eggs. Breeding goldfish can be a laborious process, though, that involves finding fertile mates and encouraging the pair to breed. It can also be expensive to ensure that the eggs incubate properly.

5. Goldfish Don’t Have Stomachs

Goldfish do not have stomachs but they do produce a lot of waste. To help keep the water clean, you will need a water filter to remove the poop and other debris from the tank. This will help ensure clean water which, in turn, ensures a long and healthy life for your fish.

Frequently Asked Questions

Do Goldfish Recognize Their Owners?

Goldfish can recognize their owners’ faces and will typically be more responsive and reactive to their owners approaching, compared to when strangers approach. However, this is likely because they know that food usually follows when that person approaches, and it doesn’t necessarily represent more of a bond than that.

Do Goldfish Learn?

Goldfish are capable of learning and this, coupled with their desire for food, means they can actually be trained. It is possible to train a goldfish to feed from your hand, or at least near it, and even to follow a target around the tank. And most will learn your preferred side at feeding time and then wait for food at that side of the tank in the future.

Can Goldfish Bond with Humans?

Goldfish don’t really bond with humans in the same way cats and dogs do. But, they do learn to recognize their owners’ faces and they do associate their owners with food being put in their tanks. Therefore, in that respect, they do form a bond of sorts with humans.

How Do You Entertain a Pet Goldfish?

You can’t walk a goldfish, but your pet fish do need stimulation. Typically, this comes in the form of tank decorations like sunken ships and plants. Your fish will be intrigued by these additions to the bottom of the tank and even once they have investigated, they will enjoy swimming between the holes and through the channels they form. You can also train your fish to swim through hoops or follow a target to give them additional stimulation and entertainment.

In Conclusion

Goldfish have been kept as pets for thousands of years, and despite the myth that they only have a very short memory span, goldfish actually have very good memories. They are also considered intelligent animals, learn to recognize their owners’ faces, and they can be taught to perform some basic tricks like swimming through hoops. Most will also learn which side of the tank you prefer to give food at and will return to that side for food in the future.

Featured Image Credit: dien, Shutterstock