RE: Iodized or Kosher salt for brine?
To make a brine, you neeed salt. I didn't see any listed in your recipe, but you did ask about it. Here is a very basic brine recipe for fish.....
1 quart Water
1/2 Cup Kosher Salt
1/2 Cup Brown Sugar
There is a big difference between all the various salts. Because of the size of the crystals, you should weigh them instead of measuring them. Here is a recap offered up over at the Virtual Weber Bullet site.....
Table salt and kosher salt do not have the same saltiness in a flavor brine when measured by volume--but they do when measured by weight.
Table salt weighs about 10 ounces per cup, while kosher salt weighs 5-8 ounces per cup, depending on the brand. If using kosher salt in a brine, you must use more than a cup to achieve the same salt flavor you would get from a cup of table salt.
The chart below shows equivalent amounts of table salt and the two most popular brands of kosher salt.
Ordinary Table Salt 1 cup
Diamond Crystal Kosher Salt 2 cups
Morton Kosher Salt 1-1/2 cups
Diamond Crystal Kosher Salt weighs about 5 ounces per cup, making it half as strong as table salt. Morton Kosher Salt weighs about 7.7 ounces per cup, making it three-fourths as strong as table salt.
For sea salts and other brands of kosher salt, use a kitchen scale to measure 10 ounces of salt. That measure will be equivalent to 1 cup of table salt in terms of its saltiness.
Once you make the brine, soak your fish for 60-90 minutes MAX!!! Any longer and it will be a large salt block. After brining, rinse thoroughly. Once rinsed, you need to let the fish dry until the pellicle forms.....this will take about an hour OR use a fan to quicken the time. Once the pellicle is formed, then you can smoke the fish. It should take about 3-4 hours at temps of 240-250º. Keep in mind....the cooking time will be affected most by the thickness of the fish!
Hope this helps!