Shima-Aji Sushi, 縞鯵 (Striped Jack)
|Category||Shiromi (white fish)|
|Size||Small (1 foot to 3 feet, 30cm to 90cm)|
|Names||White Trevally, Striped Jack, Striped Horse Mackerel|
|Season||June through August|
|Served||Raw as nigiri|
Shima-aji, or Japanese “striped jack,” is a common point of confusion for many sushi eaters. The shima means “striped” and aji is Japanese “horse mackerel,” or “jack.” But shima-aji and aji make two very different types of sushi. Aji would be more familiar to those who have eaten the more common saba (mackerel), which is a bit more fatty and oily with a “fishier” finish. The shima variety is quite a bit leaner and more delicate, closer to kanpachi.
Shima-aji can be found all over the Atlantic Ocean, and even in the Pacific and Indian oceans. For sushi, it is caught off the Japanese coast in shallow waters around 650 feet. Today it is very heavily farmed, which supplies most of the demand for sushi. Only very high-end sushi-ya serve wild-caught shima-aji.
Shima-aji tastes like a cross between saba (mackerel) and kanpachi (greater amberjack, like leaner yellowtail). It’s light and buttery with very tender flesh and just a bit of fat. When very fresh, it has a firm texture and finishes with sweet notes. Many experienced sushi tasters count it amongst their favorites.
Wild shima-aji is available all year round but its prime season is the summer. It’s a medium-sized fish, growing to three feet as an adult, but is best for sushi when it is younger, around one foot long. When in season, most of the catch will be this ideal length and quite sweet. Farmed shima-aji does not fluctuate much seasonally. It is available all year for sushi.
The Japanese often age shima-aji for 1-2 days to bring out its lighter flavor, which is very mild right after being caught. After a couple of days, the flesh breaks down just enough to become slightly tender and quite sweet.
Shima-aji is most commonly served as nigiri or sashimi. Maki (rolls) are an uncommon preparation, perhaps because its taste is not strong enough to come through when surrounded by nori and rice. Typical toppings include grated daikon (radish), gari (ginger), and negi (scallion / green onion), but the most traditional preparation is to simply brush with nikiri (sweetened soy sauce).