First of all, it’s important that you buy good quality fish. Fresh fish should have bright, clear eyes and scales should be shiny and cling tightly to the skin. Also use your nose – there should not be an overpowering fishy smell.
Frozen fish should be free of ice crystals and freezer burn, and show no signs of thawed juices. Also make sure the package it comes in is tightly sealed and clean. And remember: never refreeze thawed fish!
Always handle your fish with care, as it bruises easily. Keep it cold and never lift it by the tail but lift it whole with both your hands. Unpackaged fish should be rinsed under running, cold water and patted dry with a paper towel before storing in a cold fridge.
When cooking your fish, follow the 10-minute per inch rule. Measure the fish at its thickest point and cook it for 10 minutes per inch (per 2.54cm). You don’t need to turn it in the oven, but do remember to add 5 minutes to the total cooking time if your fish is wrapped in foil or covered in sauce.
When the fish is opaque and flakes easily with a fork, it’s ready!