Preheat oven to 180 degrees C. Grease a baking dish. Combine flour and breadcrumbs on a plate.
Dip each fish fillet into the melted butter, then press each side into the breadcrumb mixture. Place in the baking dish. Place a bit of bacon on top of each fillet, brush with butter. Bake in preheated oven for about 10 minutes.
Remove from oven. Preheat ovens griller. Top fish with banana then grill for 4 minutes more. Serve.
You can use any white fish for this recipe, such as hoki, tarakihi or even cod, but it is best with gurnard.