Dave Kellam

If You Knew Sushi examines the world’s biggest seafood market, where a bluefin tuna can fetch the price of a small home. Japanese fish buyers have a finely honed craft.

“I tell you, Nicky, these Japanese guys, they take a little, thin slice from the tail, hold it to the light, look at it for a minute, then make an offer. God knows what they see.”

What the Japanese buying agent determines by his quick and practiced analysis of that sliver of tail is an indication of the tuna’s inner color, its oil content, and the presence, if any, of parasitic disease. A smooth-grained and marbled tail is a prime indication of quality. The richness of the tuna’s lipid content, its fat, can be gauged by how slippery the slice of tail feels between the fingers. Pockmarks reveal parasites. It’s a complex diagnostic method that is mastered only with years of practice. The overall form and color of the tuna are also quickly assessed at the same time. The ideal of these qualities, inner and outer—the word for this ideal is kata—is also a bit of a mystery to outsiders.