I call her 'half fin'. She's in full cleaning mode with her tail almost parallel with her body. That long tail fin is usually straight up, unless she wants to allow the little cleaning fish to approach her without getting eaten!
Here's another one from a distance. Her tail is not quite parallel to her body...yet! She's a bit larger too.
It's good practice to be able to access deep relaxation while having a shark encounter. Either you can or you can't. There's NO faking it;^)