About 6 months later the researchers played the sound again over a loudspeaker and many of the goldfish returned to where the sound was playing.
They live in groups of up to 10 or more fish.
He also has a habit of referring to himself in third person when he is talking about himself.
The fish also performed better than chance at identifying unfamiliar faces, even when they were presented with a series of pictures of familiar faces and unfamiliar ones.
Siblings Matthew and Hayley Wright won two goldfish in 1977 at a funfair in Brockworth, Gloucester, England, naming them Splish and Splash.
Goldfish have memories that last several months, not a few seconds like many believe.