I started my CO2 about three weeks ago, very slowly ramped it up to where I am now with zero affect on my 20 fish. I have had 5 Madagascar rainbows in quarantine for two weeks and am in the process of introducing them into my 150. After slowly adding tank water to the bag as they floated for an hour I released one into the tank. He immediately went to the surface and is gasping for air. I have not released the other 4 into the tank until I observe the first one for a while and see if he acclimates. I have a hard time believing that this normal acclimation behavior, or is it? Do I have my CO2 too high even though the other fish have never shown even the slightest sign of CO2 poisoning?