Almost 8,000kg of glass are being replaced at Sea Life Blackpool.
Thirteen sharks and more than 300 fish have been removed while the new glass is fitted.
It is the first time in 23 years the tank has been emptied.
More top news
The family of Robert Hart are grieving afresh today after his brother-in-law died trying to rescue his children from the sea.
Manchester United defender Marcos Rojo believes team-mate Angel di Maria is one of the best players in the world.
Widnes' top-eight Super League hopes have been dealt a major blow with the loss of skipper Kevin Brown for at least six weeks.