I was thinking exactly the same thing other an the continuous buzzing of the water pump. Also when the grow bed drains, there's huge rush of water. Might be unnerving for the little creatures, but they'd sure have great dissolved oxygen to 'breathe.'
In the mini AP unit I recently built, I put a few goldfish in there to eat the food that gets flushed over from the FT. They are doing well. It is amusing to watch the two groups of fish look at each other through the glass.
hehe. thanks for the suggestions. I forgot about the water fluctuation. I'm still in plan and design mode.