Season the frozen fish with salt, pepper & garlic powder and set aside.
In a large 9 x 13 pyrex dish or roasting pan, toss the potatoes, paprika, garlic cloves, salt, pepper, piri-piri sauce, ketchup, cumin, onions, ketchup, wine and olive oil together.
Place the dish in the middle of the oven and bake for 35 minutes, or until the potatoes are almost tender, tossing regularly. Toss the fish in the sauce then place on top of the potatoes. Bake until the fish is tender and flaky (basting and turning 2 or 3 times) and potatoes are tender.