Fish is easy to overcook, which makes the prospect of reheating leftovers even more daunting. Here's how to do it.
Fish is notoriously susceptible to overcooking, so reheating previously cooked fillets is something that makes nearly all cooks balk. But since almost everyone has leftover fish from time to time, we decided to figure out the best approach to warming it up.
As we suspected, we had far more success reheating thick fillets and steaks than thin ones. Both swordfish and halibut steaks reheated nicely, retaining their moisture well and with no detectable change in flavor. Likewise, salmon reheated well, but be aware that, thanks to the oxidation of its abundant fatty acids into strong-smelling aldehydes, doing so brought out a bit more of the fish’s pungent aroma. There was little we could do to prevent trout from drying out and overcooking when heated a second time.
To reheat thicker fish fillets, use this gentle approach: Place the fillets on a wire rack set in a rimmed baking sheet, cover them with foil (to prevent the exteriors of the fish from drying out), and heat them in a 275-degree oven until they register 125 to 130 degrees, about 15 minutes for 1-inch-thick fillets (timing varies according to fillet size). We recommend serving leftover cooked thin fish in cold applications like salads.