How to Make It
Cook paccheri according to package directions. Drain pasta, reserving 1½ cups cooking water.
Soak bread in stock for 2 to 3 minutes. Gently squeeze out excess moisture. Combine bread, walnuts, basil, parsley, vinegar, garlic, ½ teaspoon of the salt, and ¼ teaspoon of the pepper in a food processor. Process until combined. With processor running, slowly add ½ cup of the olive oil in a steady stream through food chute, and process until smooth. Stir in cheese. Place agliata sauce in a bowl; set aside.
Heat remaining 2 tablespoons oil in a large skillet over medium-high. Season fish with remaining 1 teaspoon salt and ½ teaspoon pepper. Cook fish in hot oil until golden brown and just cooked through, about 4 minutes per side. Let cool slightly. Peel skin from fillets; discard skin. Break fish into chunks, and set aside.
Add agliata sauce, pasta, and 1 cup of the reserved cooking water to a large skillet. Cook over low, tossing often and adding remaining ½ cup cooking water as needed, until sauce is slightly thickened and coats pasta. Add fish to pasta, and toss once to combine. Divide among 4 bowls, and top with Citrus Breadcrumbs. Serve immediately.