Pyrmont Fish Market's 36-hour marathon kicks off in original building for last time

The Sydney Pyrmont Fish Markets 36-hour marathon is underway for the last time before the markets move to a new building.

More than 100,000 customers will move through the fish markets over the 36-hour marathon, which kicked off in Pyrmont today.

More than 3500 tonnes of seafood will be sold every minute up until 5pm on Christmas Eve, including 120 tonnes of prawns and close to 840,000 oysters.

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"This might be one of the best seafood years we've had in the past 12 years in terms of what's available," Michael Huls added.

The vendors told 9News they were geared up and ready to go.

"We've had plenty of practice, this is our 29th running of the 36-hour marathon and everything that goes with it," Gus Dannoun from Sydney Fish Markets said.

People travel from far a wide to visit the iconic fish markets, with one couple telling 9News they drove all the way from Lithgow, west of the Blue Mountains.

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It's the last time the non-stop seafood marathon will be held in the old building before it moves next door to the new Blackwattle Bay building.

Next year's marathon is expected to be even bigger, with more space in the new building.