I have a biocube 29. Currently have a lawnmower blenny and a black and white damsel. I've always loved bangai cardinals. Can I add 2 in current setup? They would be the end of my stocking list. I'm worried about the damsel picking on such relaxed fish. If I can't do the pair what else would be highly active? I tried a 6line but I must have acclimated him wrong or something because it dissapeared in a couple days.