Michelle,

I haven't had a problem with fish sticking to the grill (use a little cooking oil on the grids). My favorite way to prepare halibut is in a packet (in the oven or on the grill.

Season the fish with salt & Lemon pepper and pinch of garlic powder
Add a pat of butter on top of the fish
Add some sliced carrots, onion slices and snow peas (optional)
Wrap it in the foil packet and cook until the fish flakes.
It's so good even my picky, will eat nothing but fish stick kids love this dish.

EXCELLENT.