You’ve probably heard that fish have a three-second memory, or that they’re incapable of feeling pain. Neither of these statements is true, but it’s telling that these misconceptions don’t crop up for other vertebrates.
Perhaps it’s because fish appear so different from us. They don’t seem to have any capacity for facial expression, or vocal communication—and we don’t even breathe the same air. Collectively, these differences put fish so far away from humans that we struggle to relate to them.
But when scientists have conducted experiments to discover more about fish—including their neurobiology, their social lives and mental faculties—they’ve found time and time again that fish are more complex than they’re often given credit for. Above all, fish seem to have more in common with us than we might like to admit.
In my research I often work with zebrafish—the aquatic lab rat. Here are five fascinating things that I, and other researchers, have discovered about them and their kind.
1. Fish lose their memory as they age
As humans age, our memories decline. Scientists work to understand the biology of cognitive decline in order to predict how we can help people age better and develop treatments for conditions such as Alzheimer’s disease and dementia.
In humans, working memory—the mental process that we use to carry out everyday tasks—declines as we get older. My colleagues and I found something similar when we observed zebrafish at six and 24 months of age swimming around in a Y-shaped maze.
We found that the older fish struggled to navigate the maze compared to younger ones. What’s more, when we designed a virtual version of the task for humans, we found that people in their 70s showed exactly the same deficits as fish.