If it was me, I would try my luck and keep the six-line wrasse in with the rest. As long as there's enough turf for everyone, I think it could be fine. Of course, if you see too much aggression or bullying, be prepared for that and know what your plan is should that come to pass. Cardinals are very slow, methodical swimmers, so you wanna make sure they're not going to get pummeled.Would I be able to get a pair of cardinal fish, and 4 chromis, and switch out the six line wrase?