Combine the cumin, coriander, paprika, sea salt and garlic powder in a small bowl. Set aside.
Wash the fish and pat dry with paper towels. Remove the paper towels and place the fish on a baking sheet.
Squeeze the lime juice over the fish and season the fish generously with the rub.
Heat oil in a large grill-style cast iron skillet over medium-high heat.
Add fish to pan, cook 3 minutes on each side or until desired degree of doneness.