The goldfish (Carassius auratus) is one of the most popular ornamental fish in the world. However, contrary to the common misconception, their memory is not limited to just 3 seconds.
First domesticated in China around 1,000 years ago, there are currently over 125 varieties of goldfish. They have an average lifespan of 10 to 15 years, with the oldest recorded goldfish dying at the age of 43, possibly with a head full of memories.
How Intelligent Are Goldfish?
Culum Brown, a fish cognition expert at Macquarie University in Australia, shared with Live Science in 2021 that: “We have known about the good memory of goldfish since the 1950s and 1960s, and in fact, they are really quite intelligent.”
Since research began exploring the intelligence and memory capacity of goldfish, findings have consistently shown that they are capable of forming long-term memories, social learning, tool use, spatial awareness, and problem-solving.
Goldfish have the surprising ability to accurately estimate distances.
In 1966, researchers at the University of Michigan conducted a study in which goldfish demonstrated an improved ability to avoid electric shocks over several days of testing, providing evidence that short-term memory is formed.
A study conducted at the University of Oxford even found that goldfish have the remarkable ability to accurately estimate distances—a feat that even humans can find challenging. They were trained to swim 70 cm to receive food, and they could accurately measure this distance even when the starting point and the stimulus changed.
Goldfish can learn to navigate mazes, as shown in scientific studies. Videos captured them moving skillfully around the laboratory, demonstrating their complex learning and memory capabilities.
The small brain size often attributed to the “stupidity” of fish does not necessarily correlate with intelligence. Notably, the brain of fish lacks a hippocampus, which is crucial for forming long-term memories.
However, fish possess a structure known as the lateral pallium, which connects events and experiences. This area has an evolutionary equivalent to parts of the mammalian brain that support learning and has a similar structure to the amygdala, which is involved in emotions.
Why Do People Think Goldfish Have a Three-Second Memory?
The myth of the goldfish’s three-second memory may stem from the fact that many are kept in small, empty tanks, limiting their ability to demonstrate intelligence. The cognitive abilities of fish may also be underestimated due to public ignorance. Many people believe that keeping fish in small tanks is acceptable, leading to unfair treatment.
Goldfish are not the only fish with remarkable memory capabilities. Research indicates that many freshwater and saltwater species exhibit unique and advanced cognitive skills.
African cichlids, a commonly farmed freshwater species, have been shown to form associations and remember these connections for up to 12 days, while studies of wild fish indicate memory retention for up to 11 months regarding negative experiences.
Zebrafish can understand quantities, and studies on cleaner fish have shown that they can recognize their own faces in reflections.
Some species have demonstrated the ability to escape mazes, and observations show fish in the wild hunting cooperatively (such as moray eels and groupers), protecting each other from predators (such as lionfish and guppies), and cleaning other fish in exchange for protection from being eaten (such as cleaning wrasses).
Fish possess a lateral pallium, a structure that connects events and experiences.
Despite clear evidence supporting the intelligence of fish, they are often mistreated within the pet trade. The animal welfare charity The Humane League explains that: “Currently, fish are suffering more than any other vertebrate because they are not only kept in the largest numbers but also face serious welfare issues, including disease, sea lice, and overcrowding in these farms.”
Currently, pet fish are often excluded from laws—such as the Humane Slaughter Act in the United States—related to the ethical slaughter of livestock to prevent unnecessary suffering, leaving around 124 billion farmed fish vulnerable to abuse and undue suffering each year.
Through numerous studies and real-world evidence, it is clear that goldfish not only have long-term memory but also possess the ability to learn, solve problems, and demonstrate remarkable intelligence. Proper care and nurturing of them not only help them live healthily but also show respect for a species with cognitive capabilities far beyond what we previously thought.
