The Guinness world record for the most expensive tuna fish was set by a single blue-fin tuna (Thunnus thynnus), weighing 342 kg (754 lb), which was sold at an auction in the Tsukji fish market in Tokyo, Japan, on 5 January 2011, where it raised 34.49 million Yen ($420,000).

Guinness World Records also recognized the world record for the most people gutting fish simultaneously, set by 1,000 people of Santoña, in Cantabria, Spain.

The bluefin tuna is a species in decline. While the Pacific variety isn’t as endangered as the West Atlantic bluefin, it’s quite telling that half of the 600 devices that researchers from Tag-A-Giant attached to Pacific bluefins were returned to the New York-based operation by fishermen seeking the $500 reward for each device.

In 2010, the 440-pound tuna’s record was beaten by the sale of a gargantuan 513-pound bluefin. Sold at Tokyo’s Tsukiji market, the most expensive tuna in the world was also purchased by a confederacy of restaurateurs—this time the owners of two sushi restaurants in Japan and the owner of one in Hong Kong.

The Platinum Arowana is an extremely rare species of Arowanafish with virtually no coloration on its body. This breed of fish is so valuable that an offer for $80,000 was recently turned down by the owner! Legend states that this fish is supposed to bring good luck, which is a big reason why it is so unbelievably expensive. This unique fish dines on a diet of insects, shrimp, fish, and frogs. They enjoy warm water of 75-82 degrees Fahrenheit.

Kiyoshi Kimura, winning bidder of the January 5 fish auction 2012 opener in Japan and president of restaurant chain Sushi-Zanmai, said he bought the fish as to give Japan a positive outlook after a difficult 2011 for the country that was marked by devastating earthquakes, nuclear plant meltdown threats and a tsunami that claimed thousands of lives.

For a president of a sushi restaurant chain in Japan, he is willing to pay the $736,000 expense for a rare bluefin tuna which now holds the title of the world’s most expensive fish ever bought at a single purchase. The fish was auctioned at Tokyo’s Tsukiji fish market and has a record of 56.49 million yen tag price.