Goldfish memory myth busted
 

A 15-year-old South Australian school student has busted the myth that goldfish have a three second memory..... Six days later, he once again placed the beacon in the water and despite not seeing it for almost a week, the fish swam to the beacon in 4.4 seconds, showing they had remembered the association between food and the beacon for at least six days.

http://www.news.com.au/dailytelegrap...001028,00.html

The Mythbusters busted that years ago.