Preheat oven to 375 F. Line a rimmed baking sheet with aluminum foil; set aside.
Rinse fish and pat dry; place on the prepared baking sheet. Season each fillet with ¼ tsp. garlic salt and pepper to taste. Divide the butter pieces, lime zest, and juice evenly among the tops of the fillets. Bake for 8 to 12 minutes or until the fish flakes easily when tested with a fork.