The myth

Goldfish have a three-second (or seven-second) memory span.

The "truth"

Keeping a fish in a small bowl is clearly an act of monstrous cruelty, and so a myth has arisen which allows pet owners to feel less guilty: that fish - in most versions, specifically goldfish - can't remember anything which happened more than a few seconds ago, and therefore never get bored with their tiny homes. (The precise number of seconds varies, but is generally seven or three - as usual in matters mythconceptional).

Ichthyologists have known for a long time that this isn't true, and in 2003 Dr Phil Gee, of the School of Psychology at the University of Plymouth, published research which blew it out of the water.