Researchers from the Technion Institute of Technology in Israel recently put the notion that fish only have a three-second memory span to the test.
Their recent study trained young fish to associate a certain sound with food over the course of a month, then released the animals into the wild. The researchers played the sound four to five months later to see if the fish would retain the association. Sure enough, the fish returned to the sound, suggesting that their memory span is at least that long.
This is not the first study disproving the myth that fish are unintelligent creatures. Other studies have indicated that they can learn to press a lever for food, navigate through mazes, recognize other fish, and even tell time.