“I wanted to meet expectations of my customers who said they wanted to eat Japan's best tuna again this year,” Kimura was quoted by Jiji Press as saying after the intense pre-dawn bidding.

“With this good tuna, I hope to help cheer up Japan,” Kimura said.

Based on the price paid - around 700,000 yen per kilogram - a single slice of sushi from the monster fish would cost diners as much as 30,000 yen.

But Kimura plans to sell it at a huge loss, for a more realistic price of up to 398 yen per portion, local media reported.

Bluefin is usually the most expensive fish available at Tsukiji.

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

Japan consumes three-quarters of the global bluefin catch, 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.

A piece of “otoro” or fatty underbelly can cost some 2,000 yen at high-end Tokyo restaurants.