Canned fish in eggplant sauce can be steamed. The glass jars used to make canned goods need to be sterilized at high temperatures before they can be used, and can be placed in boiling water for 3-5 minutes, or placed in a large pot over high heat to steam for about 5 minutes. Also note that when steaming canning jars, the steamer and steamer should be cleaned to avoid the oil in the pot staining the jars.