'Three second' goldfish memory is a myth! Pets can recall the paths they swam on a year ago, scientist says

It's a piece of scientific myth so well-known that it has become a common insult. 

But scientists now say that the 'three second' goldfish memory is a myth.

Professor Culum Brown, an expert in fish cognition from Macquarie University in Sydney, argues that goldfish, and almost all other fish, have impeccable memories for places and even the identities of their friends. 

In a series of trials, Professor Brown found that rainbow fish were able to remember a path through a simulated trawl net for up to a year.

Professor Brown told BBC Radio 4's Naturebang programme: 'I dare say that any animal that doesn't have that sort of capacity, fish or otherwise, would not last long in the real world.'

Goldfish are often maligned for their poor memory and cognitive skills, but Professor Brown says the reality could not be more different.

He says: 'No matter where you go in the world, people have a very, very low expectation about a goldfish's memory.

'And I don't think it's goldfish in particular - I think goldfish are symbolic of fishes in general. There's this general tale that fishes have this awful capacity for memory.'

As Professor Brown points out, if this were true, fish would be unable to learn any new behaviours or learn how to adapt to changes in their environment.

But despite how common this belief may be, scientists have known for years that fish have impressive learning abilities.

To highlight this point, Professor Brown designed an experiment to demonstrate how fish learn to escape the clutches of fishing vessels.

He placed rainbow fish in a tank with a miniature model of a trawler net in which he had cut a single hole to act as an escape route. 

As he ran the experiment again and again, he noticed that the fish became faster at finding the escape hole.

Professor Brown says: 'By the end of four or five trials, they would basically be swimming calmly in front of the net.

'And about halfway down the aquarium, they would literally do a U-turn and swim directly through the hole. And I was just like, wow, this is incredible.'

Most surprisingly, when he returned the fish to the apparatus 11 months later, they were still able to find the hole on their first try. 

This is not the only study to demonstrate that fish have a far better memory than their reputation would suggest.

In 2022, researchers from Oxford University trained nine Goldfish to swim exactly 70cm through their tank before stopping to receive a treat.

The researchers found that the fish were able to use stripes on the walls of the tank to map out their environment in the same way that fish would use rocks and seaweed in the wild. 

Likewise, Professor Brown points out that many fish are able to return to their breeding grounds despite having spent years away at sea.

He says: 'We all know about trout and salmon coming back to exactly the same place to breed every year. And that's actually commonplace amongst many territory fishers.

'There's some fantastic evidence of the migratory patterns and spawning behaviour and foraging grounds of fishers being culturally passed from individual to individual across generations.'

For instance, the UK is home to the Atlantic salmon which lays its eggs in the gravel of freshwater streams along the west coast of Scotland.  

After hatching, the young salmon spend between months and years in freshwater before making their way to the sea.

The salmon might remain at sea for up to six years as they mature into adults before swimming back up the stream in 'salmon runs' during the autumn. 

Professor Brown says: 'In actual fact, if you break it down, most of the behaviours that most animals do are adapted and fine tuned by learning a memory.'

Fish, Professor Brown argues, even have the ability to recognise each other and preferentially choose to hang out with fish they have met before.  

He adds that, in hindsight, looking back, the belief that a fish's memory is short is 'just a nuts idea'.

'It kind of gives us an excuse to treat them poorly, because if we have a low opinion of their intelligence, then perhaps we can abuse them and get away with it,' Professor Brown concludes.