Expect some pecking order stuff, but you may be OK. IMO & IME; two tangs of the same species (or even genus, especially Zebrasoma genus) are much more likely to constantly fight & maim than 3. You'll often see groups of YTs at a LFS; but never 3. You'll hear/read all sorts of stuff about what tro introduce and when. IMO & IME; I really don't think that matters much and is an "individual fish' thing. But I would add the two PBTs together. Also, because it is so difficult, I'd try to add the Achilles first.
Just my opinion, and assuming the tank is big enough; but I think a lot of "what works" in tanks with a lot of tangs is related to how much fish squabbling the hobbyist can put up with, especially at first. If a hobbyist can't stand some minor battles, this isn't a tank for him. I don't think this is cruel, just normal tang behavior on the reef as well as our tanks. Tangs come armed with a switchblade and some nasty looking cuts aren't that rare and to be expected. . But things usually settle down and the pecking order is established. But there are some fish that just need to be moved. Some are too nasty and some too wussy. A wussy tang in a tank like this has no chance; its tankmates won't leave it alone.
Agree with everything you said. However, lately I've kind of changed my mind about stocking. I used to think that as long as the fish don't break out in nasty fights, it's ok to keep them together. A couple of months ago (you may remember), I tried adding an emperor angel to my tank with an existing adult French angel, and immediately the French went to kill the emperor. The emperor did not fight back and simply tried to escape, but in the end got stuck to the power head. Ten minutes later I decided to remove the emperor, but even after I did that, the French sat on the bottom breathing really hard for more than an hour. I could see in the French's eyes that it was under a lot of stress, even though it was the aggressor. This tells me that when there are significant incompatibilities among any tank mates, both the aggressor and aggressee are stressed, and this does make sense. If I have to constantly worry that my food will be eaten by other people, I would be stressed as well.
As a result, I now stock my tanks in a way that ensures there are no chasings whatsoever. A little bit of squabble, such as when a fish gets driven out of another one's territory, is fine, but constant aggression is not allowed in my books anymore. I think this is the only way to ensure my fish live a nice, long life.
Sandwi, how did you introduce your emperor to your tank during this last dust up? Acclimation box or any division in the tank? I have had some success with placing a new fish in a clear acclimation box and after a day or so, the locals calm down ... It's not been with two alpha fish like a french and emperor in your example, which is a tough combo. Just curious and did you upgrade your tank size this last year?
Sandiwi54,
Congrats on the new tank. I am hoping to do the same this year if I have time to put in the work. Thanks for the link, I'll check it out.
Just my opinion, and assuming the tank is big enough; but I think a lot of "what works" in tanks with a lot of tangs is related to how much fish squabbling the hobbyist can put up with, especially at first. If a hobbyist can't stand some minor battles, this isn't a tank for him. I don't think this is cruel, just normal tang behavior on the reef as well as our tanks. Tangs come armed with a switchblade and some nasty looking cuts aren't that rare and to be expected. . But things usually settle down and the pecking order is established. But there are some fish that just need to be moved. Some are too nasty and some too wussy. A wussy tang in a tank like this has no chance; its tankmates won't leave it alone.