All-purpose flour doesn't actually work the best all the time, and when it comes to frying fish, two different types of flour ...

Rice flour absorbs less fat and moisture ... Therefore, I also tested GF fried fish using frozen and thawed cod.

This finely-textured powder clings onto fish effectively, and when fried, a rice flour coating soaks up far less oil than wheat flours (such as all-purpose). This yields a lighter and crispier finish.