I have been smoking my fish for over 30 years now. I found when it comes to a real good brine use Apple juice and float an egg. that if the brine you use is cider it gets real sweet.
Never close the vent, your fish will have the texture of smoked mashed potatoes.
I let the vent stay open no more than 1/4%.
never be afraid of mixing wood, but when you smoke a turkey go Hickory.
I love smoking cornish game hens..I ues Apple and mix my wood with Maple and Apple.