A deep-pocketed restaurateur shelled out nearly three-quarters of a million dollars for a single tuna fish at Japan's Tsukiji fish market on Thursday, smashing a previous record.

The 269-kilogramme (592-pound) bluefin -- caught off the coast of Japan's northern Aomori prefecture -- stood at an eye-popping 56.49 million yen ($736,500) when the hammer came down in the first auction of the year.

The figure dwarfs the previous high of 32.49 million yen paid at last year's inaugural auction at Tsukiji, a huge working market that also features on many Tokyo tourist itineraries.

Thursday's winning bidder was Kiyoshi Kimura, president of the company that runs the popular Sushi-Zanmai chain.

At around 210,000 yen per kilogramme, a single slice of sushi could cost as much as 5,000 yen, but the firm plans to sell it at a more regular price of up to 418 yen, local media reported.

"I wanted to win the best tuna so that Japanese customers, not overseas, can enjoy it," Kimura said, referring to a Hong Kong sushi restaurant owner who bought the previous year's record tuna.

Decades of overfishing have seen global tuna stocks crash, leading some Western nations to call for a ban on endangered Atlantic bluefin tuna.

Japan consumes three-quarters of the global catch of bluefin, a highly prized sushi ingredient known in Japan as "kuro maguro" (black tuna) and dubbed by sushi connoisseurs the "black diamond" because of its scarcity.