Thanks for the tips! I've been wiping the buildup off of the roof of the smoker regularly, so it must be the moisture from the fish. I usually let my pieces dry for a couple of hours in a cold oven, but will try the fan method and dry them longer. I'm just concerned that my smoker isn't venting properly, or that I'm trying to smoke too much at once, or...well, we'll see with this next batch of silvers...