Preheat your oven to 190°C (375°F). Gather your ingredients and equipment.

In a medium saucepan, heat olive oil over medium heat. Add chopped onions and sauté until translucent, about 3–4 minutes. Then add minced garlic and stir for an additional minute.

Remove from heat, stir in crab meat, cream cheese, Old Bay seasoning, and salt and pepper. Mix until well combined.

Place whitefish skin-side down on a cutting board, remove bones and skin if needed. Spread crab filling evenly over each fillet.

Roll each fillet up with the seam side down and arrange in a greased baking pan.

In a small bowl, mix melted butter and lemon juice. Pour this over the rolled fish fillets.

Bake in the preheated oven for 20-25 minutes or until the fish flakes easily with a fork.

Let it rest for a few minutes before serving warm, accompanied by lemon wedges and a light salad or steamed vegetables.