I don't think I'll worry about it. The fish that I've seen dwelling around
the surface of the water are not at all gasping for air...that's probably
where they are most comfortable sleeping. Since I do use a "waterfall" type

I notice many of my rainbows hanging near the surface at night. But,
my SAEs, which are known to be VERY sensitive to low O2 levels,
are sleeping on leaves at the very bottom of the tank. I agree that
it's probably just where they like to sleep.

Clearly, if you see fish gasping at the surface, then fix the problem,
regardless of what any amount of experience says!


Chuck Gadd
http://www.csd.net/~cgadd/aqua