Preheat grill to 400oF. Tear tin foil into rectangles that will wrap each piece of fish generously. Spray the tin foil with no stick spray. Sprinkle fennel seeds on the tin foil.Set the fish on the foil, skin side down. Sprinkle with fresh orange zest. Season with salt and pepper. Sprinkle with a pinch of chilli powder (more if you like it spicy). Squeeze juice from the orange over top. Add to the top a small pat of butter.Closeup the foil and place on the grill. Cook skin side down for about 8 minutes then check for doneness. This can also go into the oven. It may require slighting longer baking time. Bake in 400oF oven.