Popular legend has it that goldfish have no memory, which is why they're happy to swim around in small glass bowls. (Actually, I had never heard this legend before, but my wife had.) Now researchers in the UK have debunked this legend. The Telegraph reports:

The urban legend of the amnesiac fish has been dealt a new blow by a study which shows that goldfish can learn to avoid parts of their tanks where they receive electric shocks for at least 24 hours, probably longer... The new study was conducted by Rebecca Dunlop, Sarah Millsopp and Peter Laming at the Queen's University of Belfast and is published in the journal Applied Animal Behaviour Science... The Belfast team showed that goldfish can remember accurately where in their tanks they receive electric shocks. The stronger the shocks, the less likely the fish were to return to the sector of the tank where they had received them. The team reported similar results with trout.

Giving fish electric shocks sounds a little cruel, but I guess you can't test them with flash cards, or put them in a maze. Of course, the legend of the forgetful fish might have arisen because goldfish are oxygen-deprived and near blindness from being kept in those little round bowls.