Pat the fish dry with paper towels and place it in a shallow dish. In a bowl, combine the lime juice, coconut oil, garlic, ginger, chilies, turmeric, cumin, coriander, black pepper, chili powder, salt, curry leaves, and grated onion to make a thick, aromatic marinade. Rub the mixture generously over both sides of the fish, making sure it is evenly coated, then cover and refrigerate for about 30 minutes. Preheat a grill or grill pan to medium-high heat and lightly oil the cooking surface. Grill the fish for approximately 4–7 minutes per side, depending on its thickness, until the exterior is lightly charred and the fish is cooked through and flakes easily. Serve immediately with fresh lime wedges, steamed rice, roshi, or a traditional Maldivian-style salad.