wow, manzanita branches look great!
I used drift wood from lake erie, one of the more contaminated lakes in ohio, and it is working fine...I just had to clean it, sterilize it by baking and boiling, and then let it sit in water while it sank while tannis and other sunstances leeched out.
The manzanita wood looked really nice when i looked it up, but it cost money.
If you are going to use live wood I wouldn't recomend any kind of pine just since it full of nasty sap...also some variates of pine sap are dangerous to humans (maybe fish too?). For example you can eat the inner sapy bark of white pine, but the shrub variety of white pine can make you mess you pants if you ever decide to eat a pine tree...but for the relavence of fish I would go with hard wood...sycamore looks great, but I think dead, dry wood would work better than live wood.