Traffic is banked up across Sydney's Anzac Bridge as thousands of people make their way to the Sydney Fish Markets.

It is the 15th anniversary of the Fish Market's 36-hour Christmas trading marathon, and the fish frenzy shows no sign of abating.

The market is hoping to sell more than 900 tonnes of seafood today.

Traders say the most popular items are prawns and oysters, with almost 1,000 oysters sold each minute.

Carmello Lombardo from De Costi Seafood says he has been working for the past 24 hours.

"Every eight hours we all take in turns in taking breaks," he said.

"The buzz is just electrifying."

The Fish Market's Managing Director Grahame Turk says he expects over a 100,000 people to visit the markets this year.

"It is getting bigger and bigger, I think a lot of people are moving towards seafood," he said.

"And you know we've got the best seafood in the world, let's face it."

The market closes at 5:00pm (AEDT).