Salt and reaching a proper internal temp are important to prevent food poisoning bacteria in your smoked fish.
There are a lot of great prior discussions on BWE and other local sites on this subject.
Here are just a couple of the many articles of fish smoking safety:
http://seafood.oregonstate.edu/.pdf%...moked-Fish.pdf
http://foodsafety.wisc.edu/assets/pd...gyourcatch.pdf
I have smoked fish for decades and have never gotten anyone sick by using brine and proper smoking temps.