Fisher King Mackerel Fillets in Tomato Sauce

mackerel fillets 50%, tomato sauce 50% (water, tomato concenrate 9%, sugar, colza oil, salt, spirit vinegar, mustard [water, mustard seeds, spirit vinegar, sugar, salt, spices], modified corn starch, spices, dried vegetables (carrot, celery, onion, leek, parsley), aroma, acidity regulator: citric acid; paprika concentrate