Preheat oven to 350 degrees F (175 degrees C). Place butter in a 9x13-inch baking dish and melt butter in the oven while it heats.
Mix crushed crackers, Parmesan cheese, oregano, basil, salt, and garlic powder in a shallow bowl. Remove baking dish from oven and dip walleye fillets into butter; gently press fillets into crumb mixture to coat both sides of each fillet. Lay the breaded fillets into the baking dish.
Bake in the preheated oven until fish is opaque and flakes easily, 25 to 30 minutes.
