In a small bowl, combine vegetable oil, chili powder, garlic powder and salt. Sprinkle over fillets and rub evenly over all sides. Tuck any thin part of the fillets under for even cooking. Put prepared fillets in a medium or large ZIPLOC Brand Zip 'n Steam Bag, placing thicker portions toward outer edge of bag. Seal bag and place in microwave.
Cook on high for 3-1/2 minutes for 1/2-in. thick fillets. If needed, continue microwaving at 30-second intervals until fillets flake easily with a fork. Let stand 1 minute before handling. Carefully open bag. Use spatula to remove fillets from bag.
Spoon lime juice and butter over fillets. Garnish the fillets with parsley.