Iwana

A river char living in the uppermost reaches of mountain streams, said to take its name from a wary habit of hiding among rocks. Salt-grilled, a delicate fat seeps out from otherwise mild flesh, the skin crisping up smoky — and the colder, clearer the water, the less any off-flavor and the firmer the bite. It peaks from early summer into autumn, ahead of spawning, when fat runs a little richer too.

Stream fishing for it uses flies or river insects, and its wariness demands moving without a sound to get close. Salted and slow-grilled is the classic approach, often skewered and cooked slowly by an open hearth so the skin turns smoky while the flesh inside stays tender. Along some streams, the grilled fish is even steeped whole in hot sake, bones included, so nothing goes to waste.

The colder the headwaters, the further from settlement, the more likely char are to live there — and the very structure of a mountain stream, cooling as elevation rises, makes this the fish found furthest upstream of all. Further downstream on the same river, yamame take over instead, the two species divided by that upstream-downstream line — water temperature alone drawing the border between them.