Did this individual observe an ammonia or nitrite spike in the system?
Or is "bacterial death" just inference?
Nicotine is generally not great for fish. I'd expect most bacteria to be
essentially unaffected by it. Nicotine affects the organism at the level
of neurotransmission, and bacteria, having no brains, just could give a
damn about it.
Wet dry filets are dependent on the air around them, and fluidized
beds are critically dependent on the dissolved oxygen content of the
water entering them. Generally, it is easier to keep air around a wet
dry (just don't pull a vacuum on it) than it is to maintain adequate DO
levels in truly highly-loaded fluidized bed.
Craig