Pecan and Hickory are from the same "family" of trees, and I find that Pecan has a milder flavor that is still very reminiscient of hickory. Before my conversion to chunks, I did use chips (especially on my kettle), and I would soak the chips and then put them in a foil packet, just to try to get them to last longer before burning up.
I generally hear people using alder with fish, but I just watched an episode of BBQ America where the gentleman standing next to Jim Minion suggested using cherry wood with salmon, which is something I'm going to have to try!! Wow, now I can list Jim as one of my favorite TV chefs. /infopop/emoticons/icon_smile.gif
I wonder how hamster-cage cedar shavings might work for salmon? /infopop/emoticons/icon_biggrin.gif JUST KIDDING...