Join Date: Feb 2004
Location: Calgary, Alberta, Canada
Truth be told, I almost had this happen once but just before it was too late I discovered that I did in fact have cherry shrimp in my tank. I didn't know I had them in the tank (it was full of large rainbows) but when the co2 was too high they were the first to the surface, where I discovered them.
It looks like cherry shrimp can be somewhat early indicators.