Undercooking is the most common mistake when cooking fish.

False. Overcooking is actually the most common mistake when cooking fish. Overcooked fish can become dry, tough, and rubbery. Fish should be cooked until it is just opaque and flakes easily with a fork. The exact cooking time will depend on the type and thickness of the fish, as well as the cooking method being used. Other common mistakes when cooking fish include using too high of a heat, not seasoning it properly, and not allowing it to rest before serving.