Ani DiFranco once sang about how goldfish have no memory and thus the "little plastic castle" in their bowl is a surprise to them every time they see it. She may have given goldfish a bad rap. A new study out of Oxford University suggests that goldfish actually have a pretty sharp memory, reports the BBC. Researchers discovered this through an experiment in which they trained the fish to swim nearly 28 inches to get a tasty reward. The fish did so in a narrow tank marked with vertical stripes, and at first researchers would provide an external signal (such as waving their hand) to prompt the fish to turn around at the right distance.
The researchers found that when they removed the hand-waving cue, the fish could still figure out the right distance to travel, apparently by using the vertical strips on the tank as a guide, per an Oxford news release. The researchers made the latter conclusion because if they subsequently manipulated the distance between the stripes, the fish would travel an incorrect distance before turning back.
"Goldfish are clearly not stupid at all, as they have a good memory for distance based on the flow of objects passing by as they swim, like stripes on their tanks," says lead researcher Dr. Adelaide Sibeaux, per the Daily Mail. "Even when I left for a week for Christmas, and came back to restart the study, they knew how to do it." The study, which appears in the Proceedings of the Royal Society B journal, explains how the feat is related to a navigational behavior known as "optic flow" and how goldfish apparently process things differently than other animals, including humans, to measure distance. (More discoveries stories.)
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