I thought this might be of interest. Very simple.
I bought a whole gutted turbot.
You need to put in some form of Turbot cage (or make one from a couple of racks wired together)
Set BGE to direct
Set it to around 200c
Start with the dark side of the turbot and then rotate (flip) every 3 - 4 minutes 
All the time baste with a mix of 30% olive oil, 70% water and as much good quality sea salt as can be dissolved into the mix.
A 1.5Kilo Turbot takes around 20 minutes.

A Turbot is a winged fish and so you need to make sure the middle (core) is cooked to around 60c whilst not burning the outer wings. You will see from the pictures that I used two 1/2 moons to deflect the heat

Have fun