Don’t let anyone shame you for buying frozen white fish. Modern freezing techniques are so good that sometimes the frozen version is fresher than the “fresh” fish at the counter. It’s flash-frozen at sea, locking in all that flaky goodness.
What Types Of Fish Are Flaky at Patricia Kaminski blog
The secret is to thaw it slowly in the fridge overnight. Pat it really, really dry with paper towels before cooking. That dryness is the key to golden, crispy edges.