The goldfish (Carassius auratus) is a freshwater fish in the carp family, commonly kept as a pet in indoor aquariums, and is one of the most popular aquarium fish.
In outdoor ponds and in the wild, goldfish can grow to about 14 inches. But when kept in small indoor aquariums, goldfish tend to be stay small in size of about 1 to 2 inches long.
Imagine how small the brain of an one-inch goldfish is.
Diminutive though they are, it turns out that the humble goldfish has a memory that spans weeks, months and even years. The science to back this up has been around for more than 60 years.
Harry Baker reports for LiveScience, May 22, 2021, that Culum Brown, an expert in fish cognition at Macquarie University in Australia, said, “We’ve known about the reasonably good memories of goldfish since the ’50s and ’60s. Despite what everybody thinks, they’re actually really intelligent.”
Brown has studied the intelligence of fish, including goldfish, for more than 25 years and thinks the misconception comes from a combination of ignorance about fish intelligence in general and guilt, because pet owners often keep them in small, boring tanks.
In reality, goldfish have such impressive memories, they’re often used as a common model for studying memory and learning in fishes. Brown said that “there are thousands of studies [on goldfish] that show fish have excellent memories. And the rate of which these studies are being published is growing exponentially.”
Here is how we know goldfish have long memories:
- A majority of studies involve food. For example, if goldfish are fed at only one side of their tank, they will quickly learn and remember to stay on that side of the tank at feeding times, regardless of whether they are actually fed. Similarly, if pushing a red paddle gains a food reward but a blue one doesn’t, goldfish quickly learn to push the red and not the blue, and will continue to show a preference for that color long after the experiment is finished. These types of experiments have also been replicated with other cues, such as bubbles and even music.
- Goldfish are good problem-solvers and have been taught to escape nets and navigate mazes. They can even remember how to repeat these tasks weeks, and even months, later.
- Other evidence suggests that goldfish can recognize and remember other individuals, even after long periods of separation.
- There is also a wealth of anecdotal evidence from goldfish owners who often observe complex behaviors in their pets when interacting with them. Some even claim that their goldfish can recognize them apart from other people.
Despite reams of research, the public’s view on goldfish memory hasn’t budged much. Brown said that’s because most people do not come across live fish in their daily lives, and even when they do, “people don’t interact with fishes the way that they do [with] other animals. This makes it easier for misconceptions and myths to be widely accepted. But public perception of fish cognition may be slowly improving as more wildlife charities and nongovernmental organizations spread the word about fish intelligence.
Properly cared for goldfish can live 20 years. Brown urges goldfish owners to consider getting their pets large tanks with enrichment objects and companion fish, as well as taking the time to play games with them and teach them tricks, because your goldfish might remember certain experiences for years to come.
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