You should keep the smoker between 150° and 160°. Smoke the fish so the thincket part registers 150° on your thermometer.Serve immdeiately or refrigerate. I use a
Thermopen which reads instantly but you can buy a cheepo which works well to. Sold at Home Depot for $10. You can brine the fish in salt, brown suger water. Here is a good basic brine to soak your fish in overnight. I like to use alder chips and apple or cherry. Any fruit wood is mild and will do a nice smoke job on fish. My favorite is alder and apple mixed.
4-5 cups water
1/4 cup pickling salt or 3/8 cup kosher salt.
1/4 cup brown sugar
2 bay leaves
1 stalk sliced celery
1/2 cup chopped fennel
1/2 cup fine chopped onion
1/2 cup white dry table wine. Chardonnay works well
2 smashed garlic cloves or 2 tbls garlic powder
Mix together all the brine ingredients and place your fish in a non-reactive container glass or plastic, cover and put in the refigerator. I usually let it soak about 12 hours, no more. Pickling salt disolves in cold water. Kosher salt should be dissolved in 1 cup of hot water then cool in freezer and add to mix. I usually add it to the cold water then add ice to to fill to 5 cups.
That should get the fish smoked for ya. I live about three hours from Lake Superior. I smoke, Coho salmon, some Atlantic salmon and lake trout. Once you do it once you can add or subtract above ingredience. I like using a little more brown sugar up to a 1/2 cup. Also experiment with dry red wines, a little more salt, etc...Have fun...Hope this helps........RTBBQ