My experience with hot-smoking fish is pretty limited, but I have not found any reason to cook low & slow for typical dining straight out of the smoker. I've smoked smaller filets at anywhere from 200* to 275*+...the outside seems to be the only thing effected by higher heat, but not always...sometimes the surface gets a bit tougher, like a bark on meat would do. High smoke chamber humidity can off-set/delay the bark/pellicle formation somewhat. Fish seems to reach it's most tender state as soon as it is firm to the touch and has an opaque interior, at which point it generally begins to flake apart, which is just about the same time it reaches minimum safe I/T. Fish is like domesticated poultry breast meat...chicken in specific...it's tender when it's at safe temp (although breast meat won't be fall-apart tender at minimum safe temp)...low & slow cooking doesn't have much effect on this as you can cook breast meat hot and fast and get equal results, unlike with lesser cuts of beef and pork (shoulder, ribs, brisket, etc) which have varying amounts of connective tissues in the muscle(s), and/or membranes surrounding the muscle group(s)...slower cooking, in this case, translates to more melting of connective tissues, and generally requires high finished I/T to reach a very tender state. Skinless fish fillets have little to nothing really holding the muscles together once they're cooked, and the outermost layer which may develop a pellicle seems to be the only thing that does hold them together. As an example, with poached fish, there is no pellicle, and that is why it falls apart so easily when serving. Of course I'm sure there may be certain species of finned fish that I've not cooked which may contradict what I just stated about fish, in general...I'm no expert on the subject, this is just my personal observations.
You may want to try a bit hotter with your favorite finned friend and see what it yields, though...never know, you may like it better than a long, slow ride...or, it may be a compromise, getting dinner on the plate sooner at the cost of developing a heavier pellicle than you'd like to have. Me? I'd try hotter with water in a pan to reduce the pellicle. Just be sure to get it out as soon as you know it's done, or the high-humidity smoke chamber can bite you in the keester (reduced pellicle/bark = more internal moisture evaporation when I/T climbs higher).
Eric
