Smoked Salmon on the grill

I use oak blocks to cook fish on an open fire. If I have the time I will use oak planks soaked in water to lay the fish on instead of the grate. Fish like salmon, blue fish, or trout are more oily that most fish and do well on an open flame. I have tried hickory, applewood, and oak and cedar and can't tell much difference in taste on an open fire but a slight difference in a smoker.