Mash together 1/2 stick (1/4 cup) unsalted butter softened, 1/2 to 1 tbsp finely chopped canned chipotle chiles in adobo to taste, plus 2 tsp adobo sauce (from can), and 1/2 tsp salt with a fork until blended. Pat fish dry and cut each fillet in half crosswise, then season with salt and pepper. Spread 1/3 cup all-purpose (for extra crunch you can also add breadcrumbs to flour) on a plate and dredge fish, knocking off excess. Heat 1 1/2 tbsp oil in a 12-inch nonstick skillet over moderately high heat until hot but not smoking, then panfry fish, skin sides up first, in batches, turning over once, until browned and just cooked through, 4 to 6 minutes. Transfer as cooked with a slotted spatula to plates and add more oil to skillet as needed. Top fish with dollops of chipotle butter.