A recently learned trick-
I use a smokehouse bar-b-que for fish. The bottom pan is filled half way with charcoal and lit. I then place a large stainless steel mixing bowl full of chips (1 or 2 pounds) on top of the burning briquettes. I then place the fish on the racks above. One load like this does the trick for about 15 pounds of fish and seems to be a nice even heat. I use the lid to regulate the heat because it can be placed askew and has a thermometer. Try it you'll like it.