Nearly every day at dawn, John Heitz falls a little bit in love. Leaning over a 150-lb. (70 kg) yellowfin tuna, the 55-year-old American, whose business is exporting fish, circles his forefinger ...

At an all-you-can-eat Japanese food expo in Manhattan, thousands lined up to witness the ceremonial carving of an enormous bluefin tuna — and try a sample. Kouama Yanta, introduced as “the greatest ...