Hard to say. On the one hand at least you have different tang body types with the zebrasoma, paracanthurus, and achilles acanthurus in the mix. On the other hand, that purple may just decide it doesn't like the new dark tang in there with it. My scopas has always been real laid back, but when I first put a new swallowtail angel in the tank, he got all bent out of shape for a couple of days. Then also I've always heard that achilles can be hard to keep anyway, so good luck to you in that respect.