alasse, the fish may have adapted somewhat, but I am sure they are stressed...stressed fish do not need to be half dead, a stressed fish can also mean a fish that does not breathe to its full potential, or when bad bacteria does enter the tank for whatever reason, the fish's immune system is unable to fight it off as well as fish in a healthier tank

certain readings in a freshwater tank must be true: ammonia 0, nitrite 0, nitrate 25-35 and under, oxygen 8.4, temperature (varies but usually between 76-82 dependent upon the load or variety of the inhabitants) and ph 6.8 to 7.6...anything that is far below any of those readings, is just asking for trouble

main thing is, a fish's immune system...the fish may appear energetic now, but if any doom hits the water column or anywhere in the tank, the fish's immune system will not have the strength to fight off the fungus, bacteria, disease etc

but hey, you're a fish hobbyist, and after several months of experience in this hobby, we do tend to get experimental - some do go way outside the requirements (even water test readings) - and only time will tell if you are doing right by the fish or not

to each their own, I'll leave it at that