In a shallow dish, combine the flour, salt, and pepper; mix well. In a large skillet, melt the butter over medium heat.
Coat the fish with the flour mixture, turning to coat completely. Place in the skillet and cook for 3 to 5 minutes per side, in batches if necessary.
Add the capers and parsley, and squeeze the lemon over the fish. Cook for 1 to 2 more minutes, or until the fish is golden and flakes easily with a fork.