Preheat the oven's broiler and set the oven rack about 6 inches from the heat source.

Place fillets on the broiler pan and squeeze lemon over fillets.

Broil in the preheated oven for 6 to 8 minutes.

Combine Parmesan, butter, Dijionnaise, garlic, and salt in a small bowl. Spread Parmesan mixture on top of fillets. Sprinkle with paprika.

Broil until topping is lightly browned and fish flakes easily with a fork, about 3 minutes.