If you don't brine, and use low temperatures to fully smoke/cook, you may find that the texture may be too dry and/or stringy to sell it commercially. If you are going without brine, maybe apply the smoke then finish it off at a higher temperature and cook until the fish is done. Such as move it to an oven at 325 - 350°F.
Just recently Cook's Illustrated performed a brine experiment using a low salt substitute that was about 40% potassium. They found the moisture of the meat was the same as if they used regular salt, but a few testers complained of a bitter after taste that is associated with potassium. But extra potassium in a diet with some people taking certain high blood pressure medications can also be an issue.