For the taco seasoning: Mix together the chili powders, coriander, cumin, garlic powder, oregano, paprika, celery salt, kosher salt and cayenne in a small bowl.
For the fish tacos: Preheat the grill to high heat. Sprinkle the fish with the oil, salt, black pepper and taco seasoning; grill the fish for 5 to 6 minutes per side to cook through. Serve the fish in warmed corn tortillas topped with shredded cabbage, yogurt, lime wedges and hot sauce, if desired.
Use the taco seasoning immediately, or store in an airtight container at room temperature for up to 6 months.