(Reuters) - Joseph Schooling, the swimmer who won Singapore's first and to date only Olympic gold medal in 2016, announced on Tuesday that he had retired from the pool at the age of 28.

Known in the city state as "Singapore's Flying Fish", Schooling stunned the swimming world when he beat his boyhood hero Michael Phelps to win the 100 metres butterfly with a time of 50.39 seconds at the Rio Olympics.