Sorry about that I didn't follow what you were asking.
Basically you put the fish in only one brine. So I did 5 pounds of tuna the other night, I put 1.65 pounds in each bag for one hour. Then I towled it off and let it air dry for a couple hours. Before putting it on the smoker I dusted with a little of the rub that would have gone in the brine.
For example for brine number one the rub would have been a tablespoon of Thyme, a couple tablespoons garlic powder, a tablespoon or White peppercorns, and a bit of lime zest. Then I would sprinkle just a little bit of it on the tuna. Not as much as if you were doing ribs or something along those lines.
For Brine 2 I would rub it with a paste of roughly T ginger T garlic powder, t ground Anchos and a t cracked blakc pepper. To make the paste I would use a little soy sauce and olive oil. Careful with the soya sauce you don't want it to be to salty.
For brine 3 I would just glaze it with a maple syrup
Anyways I hope this makes a little more sense and if you have any questions just ask away.
Clark