fish recovery after CO2 dump

[Brown_D at kids_wustl.edu]

It wasn't an end-of-tank problem, but probably a mistake adjusting the
wrong needle valve to reset the rate (after a blackout, which did work well
on the algae), and I yesterday I found a tank with gasping fish and CO2
bubbling too fast to count.  After turning off the CO2, a fast water
change, and adding an airstone, the fish mostly seemed to recover well.
Today, however, one fish was still swimming very erratically although not
gasping.  If this represents permanent residual brain damage I will
euthanize the fish, but if there is a reasonable hope of further recovery
more than 24hrs after a CO2 overdose I'd give the fish more time.  Have any
of you seen a fish who continued to improve more than 24hrs after a CO2
problem like this?

Diane Brown in St. Louis