It’s totally OK to use frozen fish in this recipe. In fact, many seafood restaurants that are far away from the ocean will typically use at least some frozen ingredients in their food.   You do not need to defrost your frozen fish prior to air frying. You just need to air fry them frozen! In fact, the additional moisture clinging to the fish when they enter the air fryer while still frozen will help prevent the fish from drying out.   Another tip for using frozen fillets is to change the fat for your sauce. Butter will typically harden upon contact with a cold surface, and soften against a hot once. That’s where the saying “a hot knife through butter” comes from. You can use olive oil rather than butter when cooking with frozen fish as the olive oil won’t harden upon contact with your frozen fish.