Pre-heat the oven to 200C. Heat the oil in a pan and add garlic and mushrooms. Cook over a medium heat for about 4 minutes. Add the stock and the seasoning and simmer for a further 4 minutes. Set aside.
Brush the kingfish fillets with olive oil and in a non-stick pan sear the fish (skin side first) for 1 minute. Turn it over and sear the other side for 30 seconds. Transfer the fish to a baking tray and place in the oven for 3 - 4 minutes.
While the fish is in the oven reheat the mushrooms and add the parsley.
Serve the fish on top of a bed of mushrooms and accompany the dish with some lightly steamed English spinach.