How to Microwave Fish
Essentially, all microwaved fish is steamed in its own juices, which makes microwaving a good choice for purists (or dieters). Because fish cooks through so fast regardless of the cooking method, you really don't save a lot of time microwaving fish, but it is convenient on days when you don't want to turn on the oven or heat up the grill. Before you start, checkout the wattage of your microwave, because fish microwaved in a higher-wattage oven (such as 650 or 700 watts) will take a third less time than in a lower-wattage oven (400 to 500 watts). In a higher-wattage oven, four 1/2- to 3/4-inch fillets placed in a microwavable dish will cook through in three to five minutes. One-inch-thick steaks will take about two minutes longer. (If you are cooking smaller quantities, such as a half-pound fish for two people, it will cook through in two to three minutes.) You can also microwave frozen fish; just add a minute or two to the cooking time.
How you arrange the fish for microwave cooking is also important. Many fish fillets are thicker in the center than on the ends. If so, fold them under to create a uniform thickness. The easiest way to arrange fish fillets for four persons is to place the fish pieces fanning out from the center of the microwavable dish.
From the "Legal Sea Foods Cookbook" by Roger Berkowitz and Jane Doerfer, illustrated by Edward Koren