The perch sandwich is a Great Lakes fish sandwich whose defining quality is the smallness of the fish. Yellow perch is a modest panfish, not a thick fillet that can be cut to fit a bun, so the sandwich is almost never one piece of fish. It is a row of small fried fillets laid side by side across the roll, and that shingled construction is the whole structural idea. Where a cod or grouper sandwich rides on a single slab, the perch sandwich is a mosaic, sweet and clean-tasting, with far more crisp edge per bite because every little fillet brings its own fried perimeter.
The craft is in the coating and the count. Perch has a delicate, almost sweet flesh that overpowers easily, so the dredge stays light: a thin flour or fine cracker or cornmeal coat, fried hot and fast so the crust sets before the slim fillet overcooks and tightens. Too heavy a batter and the fish disappears under it; the point of perch is the perch. The fillets are arranged to cover the bun edge to edge so no bite is all bread, and the roll is kept soft and unassertive because a fragile fish should not have to fight a crusty loaf. Tartar sauce or a squeeze of lemon supplies the acid the lean fish wants, and shredded lettuce or a pickle adds the cold crunch the fry lacks. This is the sandwich form of the Friday fish fry that defines the region's table, the same fish moved from plate to bun.
The perch sandwich belongs to the inland branch of the American fish sandwich, the one that follows the lake rather than the ocean. Walleye runs a firmer, larger fillet through the same fryer; lake trout, in its Baltimore reading, is a different fish under a similar coat; the broader fish fry sandwich generalizes the whole idea. The version on rye with raw onion, and the version doubled into a bun-busting stack, are local forks on this exact build. Those deserve their own articles rather than being crowded in here.