Cooking fish is relatively easy, and there are lots of different ways to prepare it, so fish certainly does not have to be boring. There are some general rules of thumb which you can use when cooking fish which will make the task easier and more enjoyable.
Before you cook fish, you need to catch it or buy it at the market. If you catch fish, be sure to clean it promptly and keep it frozen until use, unless you plan to use it within two days, in which case it can be refrigerated. In the market, look for fish which has a sweet or neutral smell, not a fishy odor, which suggests that the fish is old. You should also seek out fish which looks firm and lightly moist. If the fish is whole, the eyes and scales should be bright, indicating that the fish is fresh or that it has been frozen and handled properly.
Frozen fish can be thawed in the fridge overnight before use. Always freeze fish if it will not be used within two days, as it spoils very rapidly. Never thaw fish at room temperature or in warm water, as this is an invitation to neighborhood bacteria. If you are a hurry, you can defrost fish in the microwave, or cook cuts of frozen fish as-is, with the fish thawing during the cooking process.
There are two things which cause things to go awry when cooking fish: cooking too long, and cooking at a temperature which is too high. Fish can turn dry and tough if it is overcooked. The cooking method you use is dependent on your personal taste, and on the type of fish involved. Overmarination can also be a problem when cooking fish, because the marinade can break the meat down, turning it mushy. Never marinate for more than 30 minutes.
Grilling is a great method for cooking fish which is very firm and sturdy, such as tuna, salmon, or shark. Grill for a few minutes on each side, ensuring that the fish cooks all the way through without drying out. Baking is good for thin cuts of fish, because you can bake the fish just long enough to cook without drying out. Broiling can be used for larger cuts of fish and fish steaks. On the stovetop, frying, poaching in a liquid like wine or broth, steaming, and sauteing work for many cuts of fish. If you have a large cut of fish which you want to bake, consider cooking it en papillote, or “in parchment,” creating a parcel of cooking parchment, foil, or thick leaves such as banana leaves which allows the fish to steam as it bakes.
Fish is done when it flakes easily under a fork and it is no longer translucent. It should have an internal temperature of 145 degrees Fahrenheit (63 degrees Celsius). Saltwater species like tuna and shark can be eaten rare, with seared tuna being very popular in some parts of the world, but freshwater fish should always be thoroughly cooked, as freshwater species often harbor harmful parasites which could make people sick.