Place the fish in a baking dish and sprinkle with the lemon grass, carrots, 1½ tablespoons of the light soy sauce and the lime juice.
Cover the baking dish with foil and bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 20–25 minutes or until a skewer will slide easily into the flesh and come out clean. Place each fish on a warm serving plate and spoon over the sauce. Garnish with coriander leaves and chilli and serve with the lemon slices.
Spoon the remaining light soy sauce into a small bowl with the chilli and serve separately.
Serve with other dishes, with boiled rice or on its own as a light meal with stir-fried or steamed vegetables.