Preheat the oven to 425 degrees . In a bowl, combine the coconut milk, curry paste, garlic and coriander; season.
Divide the carrots, onion and basil among four 18-inch pieces of foil, placing the ingredients in the center. Top each portion with a fillet and a quarter of the coconut mixture. Fold the foil over the fish and crimp all the edges to seal.
Place the foil packets on a baking sheet and bake until the fish is opaque and flaky and the carrots are tender, about 15 minutes. Remove the packets from the oven and let rest 1 minute. Open the packets and serve with the rice.