Ideally, you'd have a fish grilling basket that you just flip. Now that you've already started... Very carefully with a few spatulas.
Discussion
I’m using a grilling basket but feels like cheating.
Surely master grill doesn’t need a basket.
I don't see a grill basket (the kind that close, with handles) in your pics. There are large ones you can get. All around the world, when I've attended fish bakes on the beach, that's how it was done. Easy flips. That, or skewer the fish and almost rotisserie style cook.