Pre-heat an oven to 200°C or 390°C and line a tray with baking paper to make cleaning easier.
Scrub the potatoes to remove all dirt or peel the potatoes to remove the skin. Cut into small cubes. (Smaller cubes bakes faster). Slice an onion and add to sweet potatoes. Grate desired amount of chilli onto potatoes, drizzle with oil, add salt and black pepper. Toss together and spread on the baking tray. Place the baking tray inside the pre-heated oven to bake.
Whiles the potatoes are baking, mix parsley, paprika, garlic, salt, black pepper and oil together on a flat plate. Place the fish fillets in the spice blend to coat, both the inside and the skin covering. Place on a plate to marinate. Marinate for about 20 minutes.
After the sweet potatoes have baked for about 20 to 30 minutes to almost cooked through, place the fish fillets on top with the skin side facing up. Spread any remaining marinade on top. Place the baking tray back into the oven and bake for about 8 to 12 minutes till the fish fillets are cooked through together with the potatoes. Serve.