River Dog
Fish Crazy
It could work, but as I said all fish are individuals, I agree with T about the Cray. As I have already said I know nothing about Bircher's. There is always a chance that you could end up losing any one of the three cichlids, you just have to keep a close eye on them and have a second plan ready to move either the aggressor or the harassed. If it were me, I would forget the Cray and have a shoal of 6 blue rainbows as dithers.