The best method to safely reheat leftover fish is in the oven. Most types of fish reheat in 10 to 12 minutes in an oven set to 450 degrees Fahrenheit.
Fish can also be reheated on the grill. Fish needs to cook 2 to 3 minutes over a medium-high heat.
Fish can be reheated in the microwave, but the results using this method vary. Heat in 2 to 3 minute intervals on medium setting until the desired temperature is reached.
Most types of fish and seafood need to reach an internal temperature of 145 degrees to prevent the risk of food-borne illness.