Marinate the fish: Whisk the: fresh lime juice, coconut oil, coconut milk, curry powder and salt together in a medium bowl. Add the fish fillets and turn to coat. Cover the bowl with plastic wrap and refrigerate for at least 1 hour or up to 3 hours.
For the sauce, whisk the yogurt, lime zest and juice, curry powder and cilantro together in a small bowl. Cover with plastic wrap and refrigerate until serving.
Heat a ridged cast iron grill pan to medium high heat.
Remove the fish from the marinade and grill without turning until it is firm and opaque throughout, 4 to 5 minutes. Transfer the fish to a plate and break it up into bite-sized pieces.
Make tortillas playable over heat and divide the fish among the tortillas.
Top tacos with some curry yogurt sauce, sliced avocado, arugula and radish and a side fresh lime wedge, delish!