Are Katsuobushi and Bonito Flakes the Same Thing?

They’re the thin curly shavings that dance in the heat of the steam when your takoyaki or okonomiyaki is served. We call them bonito flakes; the Japanese name is katsuobushi. They’re shaved dried fish, an ingredient for making dashi.

We’ve been buying and using bonito flakes at home for over a decade. When it started appearing in groceries and supermarkets (Japanese groceries were not the norm here ten years ago), only one brand was available. Big pack or small pack, the content is the same. Ultra thin shavings of pink dried fish. And that led me to think that all bonito flakes are created equal.

It wasn’t until I went to Japan that I realized my misunderstanding. “Bonito flakes” isn’t even an accurate term to use for katsuobushi.

Katsuobushi is dried, fermented and smoked skipjack tuna

How this Japanese ingredient came to be known to English speakers as “bonito flakes” may be a matter of convenience. It is, after all, much easier to say and spell bonito flakes than katsuobushi.

But the truth is, katsuobushi does not translate to bonito flakes. Katsuobusi is made with skipjack tuna. Bonito is a different fish — a cheaper substitute for skipjack tuna. So, when you go to the grocery and pick up a bag of katsuobushi, it’s really hard to tell if you’re getting skipjack tuna or bonito.

But does it really matter if you ended up with a bag of dried, fermented and smoked bonito flakes rather than skipjack tuna? More on that later. First…

How does fish get firm and hard enough that it can be shaved so thinly?

It’s all about the process of making katsuobushi. The fish is filleted, poached, smoked then, for true katsuobushi, sun-dried and fermented. The entire process takes months. At the end of the curing period, the fish is free from moisture and hard enough to shave.

In the market, “bonito flakes” is the generic term for all Japanese shaved dried fish — fermented or not.

Why do bonito flakes come in different colors?

Right. I didn’t even know they did until I found myself facing shelves after shelves after shelves of shaved dried fish at Takashimaya in Osaka. I was so wide-eyed with awe. Pinkish, golden, some with strips of brown… Even the size and thickness of the shavings varied. Some were larger. Some were thicker…

It turns out that the color has to do with the part of the fish used. The brown strips are the dark meat of the fish. According to a Japanese blogger, the more dark meat in the flakes, the stronger the flavor.

Cooking with bonito flakes at home

And we ge to the part where we ask the obvious questions. Does it really matter if your bonito flakes are from skipjack tuna or the cheaper bonito? Does it matter too if the shavings are light pink or a deep gold with brown strips?

Perhaps, for the more seasoned and discerning Japanese cooks, these things matter. Some say the thinnest bonito flakes are best as garnish while the thicker shavings, especially the kind with dark meat, are more suited for making soup.

At home, we use them all interchangeably. In fact, to be quite honest, after experiencing the bolder umami flavors of the thicker deep gold flakes with brown strips, I didn’t want to go back to the generic stuff found in local groceries. The thicker flakes are so flavorful that, when added to plain congee or rice, you get a delicious meal.