01 - Set oven to 400°F and line a baking sheet with parchment paper; lightly oil or spray the surface.
02 - Cut fish fillets into 1-inch bite-sized pieces.
03 - Whisk lemon juice, olive oil, Dijon mustard, salt, and pepper in a bowl; add fish cubes and toss gently. Let marinate for 10 minutes.
04 - Combine panko breadcrumbs, grated Parmesan, sweet paprika, and dried parsley in a shallow dish.
05 - Remove fish from marinade, letting excess drip off, then roll each piece in breadcrumb mixture, pressing lightly to adhere.
06 - Place coated fish bites on the prepared baking sheet and lightly spray or drizzle with olive oil.
07 - Bake for 16 to 18 minutes, turning the bites once halfway through until golden and cooked through.
08 - Serve fish bites immediately with lemon wedges or preferred dipping sauce.