He was upfront about the disaster in the apartment's TradeMe advertisement, which was listed on Friday, detailing the reasons behind the price drop.
"Believe it or not a fish tank in the apartment above overflowed & wrecked the apartment below. The good news is that the fish tank is now long gone.
"The great news is that for sale now is a completely blank canvas - stripped out to a bare shell of its former glory and screaming out for someone with vision to create whatever they want," the ad states.
The one-bedroom apartment boasts huge harbour views and has a single garage and communal garden - but will also need earthquake strengthening work over the next 15 years.
It was last sold in a pre-renovated state for $1.85 million.
"This was once one of the most amazing apartments on Oriental Parade with a fit out that would have won awards and an art collection to match," the ad reads.
The owner of the property was a high-profile Wellington resident who did not want to be identified, Mr Morley-Hall told Fairfax Media.
Fish tanks can go up to 1000L - a hefty amount of water compared to your average goldfish-sized tank.
But Hollywood Fish Farm manager Rebecca Buchan told Fairfax that custom-sized tanks could be made.
"You could potentially make a tank up to whatever size you want if you had the money," she said.
Insurance Council chief executive Tim Grafton said he had heard of upstairs swimming pools leaking but did not know how frequently fish tanks caused leaking issues.
He told Fairfax the damage should be covered if the property owners had insurance.
"If the person below has damage, their insurance company would be looking to provide cover and might look to go for the owner upstairs for causing the damage," he said.