thats what i love about having almost all atmos bbreathers in my tank, they just come up and breathe oxy levels dont really matter, at least you were able to save one!! you did all you could given the circumstances, all you can really do is prepare so if something like this happens again you can save your fish, the october storm that hit buffalo in 2009 killed mad of my friends fish, i hadnt really gotten into it at that point but i helped them clean out the dead cichlids etc. so for sure invest in a battery powered air pump, that at the least will keep the fish alive till the filter heater etc comes back on!