Heat oven to 450°F. Lightly coat a roasting pan with vegetable cooking spray. Arrange the cod fillets skin-side down. Sprinkle with the chili powder, oregano, and salt. Roast 5 to 7 minutes or until the cod is just opaque and flakes when tested with a fork.
Meanwhile, melt the butter in a small skillet over medium-low heat. Cook, swirling constantly, just until the butter begins to brown. Add the cumin and lime juice and continue to cook, swirling 1 minute longer.
Remove the cod from the oven. Set aside half the cod for another use. Drizzle the cumin-lime butter over the remaining cod. Serve.