I have been slowly increasing my co2 bit by bit as I and still battling slight bba issue. My lp ate are growing well, pearling well. I have bunch of oto, Malayan shrimps, tucanos, clowns killie, hastatus and 3 red coral pencilfish. Everyday for the last week or so, one of my three pencilfish, will start being at the top of the water. Seemingly struggling with the level of co2. The rest of my 30-40 fishes does not even seem to be having issues. I am a little puzzled what I should do now. The penclfish does is struggling seems to be al right but I dun want to torture the little guy any longer. How can this be anyway?