Australian Science and Mathematics School in Adelaide.
"We are told that a goldfish has a memory span of less than three seconds... I wanted to challenge this theory as I believe it is a myth intended to make us feel less guilty about keeping fish in small tanks." Rory said.
His experiments involved placing a beacon in the fish tank at feeding time each day and measuring the time it took for fish to swim and obtain their food reward. The time taken reduced dramatically over a 3 week period, from a minute to a few seconds at which point Rory removed the beacon from the feeding process.
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.
"My results strongly showed that goldfish can retain knowledge for at least six days," Rory said.
http://www.livenews.com.au/Articles/2008/02/18/SA_schoolboy_explodes_fishmemory_myth to news article