Curious Question: Do goldfish really have a three-second memory?

Martin Fone wonders whether everyone's favourite pet fish has greater cognitive abilities than we give it credit for.

About four million households in the UK own fish, which equates to roughly 14% of the population, according to the Ornamental Aquatic Trade Association. Attractive, colourful, easy on the eye and calming, ornamental fish offer a low maintenance alternative to cats and dogs and even spare your furniture.

For many children of my generation, a goldfish was the first introduction to the delights and responsibilities of pet ownership, often acquired accidentally, given away as a prize at a fair. The Animal Welfare Act of 2006 put an end to this practice, at least if the recipient was a minor.

Transporting one home was a challenge. When the water-filled plastic bag containing a goldfish was dropped on a bus, my aunt showed remarkable presence of mind by scooping the fish up and keeping it hydrated by inviting her fellow passengers to deposit some saliva into the bag. It survived its ordeal.

The origins of the goldfish, Carassius auratus, to give it its taxonomic name, can be traced to the carp bred by the Chinese for food. Normally grey or silver in colour, it would occasionally have a genetic mutation producing a fish with red, yellow, or orange scales. Buddhists revered rare creatures, so instead of putting a brightly coloured carp into the cooking pot, they placed it into ornamental ponds and water gardens, a practice reported on in official records from around 975AD.

Fish coloured yellow or gold, the imperial colours, were reserved exclusively for the Chinese rulers of the Song dynasty and it was an offence for commoners to keep them. Rather than relying on the vagaries of genetic mutation, experiments began in the ponds at Te Shou Palace in Hangchow city from 1163 to see whether fish could be crossbred to exaggerate the colours that were most pleasing to the eye.

By the 14th century, it was common to keep fish in bowls. This meant that the fish could be bred to develop characteristics that would either not have been noticeable in a pond or would have been prejudicial to their survival. Double or fan tails, anal fins, shortened bodies, eyes as big as their bodies, matt scales and calico colouration were especially popular physical traits, establishing the blueprint for many of the 250 or so varieties that we know today.

Orange veil-tail goldfish

As nearly everyone had a bowl, even if they did not own a pond, it also meant that more people could keep them. With ownership democratised, news of these fabulous fish percolated to the wider world. The first goldfish were exported to Japan in 1603 and eight years later some made their way to Portugal, along with shipments of edible carp. Soon, goldfish were all the rage in Europe, but fish enthusiasts were entirely reliant upon imports from China for their stock until the Dutch, in 1728, discovered the secret to successful breeding.

The opening of the first public aquarium at London Zoo in May 1853, known as the Fish House and constructed like a greenhouse, prompted an increasing interest in keeping fish. Goldfish soon became a popular pet and were even given by Victorian husbands to their wives to celebrate their first wedding anniversary.

Goldfish did not arrive in America until the late 19th-century, and they were very much a novelty. Perhaps that explains why any resident of Baltimore or Washington DC simply had to write a letter of support to their congressman for the Commission of Fish and Fisheries to send them one in the post, a testament to the speed and care of the US postal system, if not their commitment to animal welfare. From 1884, twenty thousand fish were given away a year, until this most curious of publicity stunts was discontinued in 1894.

The rise of the goldfish in America was due to Eugene Shipman. Inheriting in 1899 a patch of swamp land in Martinsville, Indiana, he had a brainwave that led him to breed goldfish commercially. His Grassyfork Fishery, starting out with only 200 breeding goldfish in 1902, had become within three decades the world’s largest goldfish hatchery, establishing Martinsville as the goldfish capital of the world.

Ownership passed to Ozark Fisheries in 1970. Today, their Martinsville facility has more than 600 ponds and sells forty million fish a year, hatching 400,000 goldfish and koi a day at the peak of the mating season.

But do goldfish really have a three second memory span? Is there any truth in it or is it an urban myth to assuage any pangs of guilt for condemning the poor creature to a life of swimming around a small bowl?

Goldfish

Goldfish have featured in more than 40,000 scientific papers. As well as being cheap and easy to breed, their ability to absorb substances, to regenerate their optic nerve, and their sensitivity to sunlight has made them ideal to study the effects of toxins and to enhance our understanding of ophthalmology and skin cancers. Inevitability, some scientists have turned their attention to the fish’s cognitive abilities.

Many experiments have concentrated on training goldfish to respond to stimuli, such as a musical note or a red Lego brick, to obtain food. Even after pausing the training for a while, researchers found that, when the process was resumed, the fish had remembered to associate the stimuli with food. Others have trained goldfish to recognise colour patterns and to run underwater obstacle courses. More than a month later, the fish had remembered what they had learned, easily completing the course without any assistance.

It also seems that goldfish have a sense of time. In a series of experiments conducted in 2003, a team from the School of Psychology at the University of Plymouth taught goldfish to earn their food by pushing a lever. Finding that the fish had soon got the hang of what they were supposed to do, the researchers modified the experiment by limiting the time at which the lever would dispense food to one hour a day. The goldfish were not in the least discombobulated, easily adapting to the new regime and only bothering with the lever at the right times of day. Clearly, goldfish are smarter than they are given credit for.

In fact, scientists have long recognised that goldfish and other small fish, such as minnows, have cognitive powers and memory spans equal to that of small mammals and have used them in many psychological studies. Some experiments have been quite bizarre. In 1969, Ralph Ryback from Boston City Hospital wondered what the impact of swimming in various alcoholic solutions would have on them. Bourbon, he found, had a greater effect than vodka, a revelation for which, I am sure, we are eternally grateful.

Clearly, a goldfish should be given plenty of space to swim around in and be provided with visual stimulation. Treat them well and they may even remember you for it. Let us hope that Joris Gijsberg followed this advice. His goldfish, measuring 18.7 inches from snout to tail fin end, was declared the world’s longest by Guinness World Records in Hapert on March 24, 2003. That was some fish.