Sydney, Feb 18 (UNI) Busting the myth that goldfish have a three second memory, a new study has revealed that they have mental capabilities to learn and remember complex concepts and retaining knowledge for at least a couple of days.

The study conducted by a 15-year-old South Australian school student, Rory Stokes, tested the commonly held theory that goldfish have short memory spans.

He also blamed humans for the ''cruelty'' of keeping them in small tanks.

It is a myth that a goldfish had a memory span of less than three seconds and no matter how small its tank was, it would always discover new places and objects, The Australian quoted Rory as saying.

The myth was intended to lessen the self guilt about keeping fish in small tanks, he added.

The three-week long experiment involved teaching a small group of fish to swim to a beacon by establishing a memory connection between the beacon and food.

He placed a beacon in the water at feeding time each day, waited 30 seconds and then sprinkled fish food around the beacon.

It was noted that the time taken for the fish to swim to the beacon reduced, from more than one minute for the first few feeds to less than five seconds by the end of the three weeks.

After the initial three-week period, the beacon was removed from the feeding process.

Six days later, the beacon was again placed in the water and it was noted the fish swam to the beacon in 4.4 seconds despite not seeing it for almost a week, showing they had remembered the association between food and the beacon for at least six days.

''My results showed that goldfish can retain knowledge for at least six days, rather indefinitely if they use it regularly,'' he said.

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