Here is my suggestions and I’m sure
@4FordFamily will concur.
No to the Naso
No to the PB
Yes to the Kole
Take your pick between Yellow and Purple but you can’t have both in a 120
Your best bet is to add both the Kole and the Zebrasoma of your choosing at the same time. Sorry to poke holes in your wish list but this is solid advice, you should also make sure these are your final fish.
I agree with what you said, PBT need 6 feet of swimming room and a 125 is too small, I’d say 180 minimum. You could possibly keep purple and yellow but they’d need to be added and purchased together, among your Kole concurrently. You can mix bristletooth tangs just fine sometimes, they’re more tolerant of each other if other tangs are present. A tomoni and kole might work although kole can be aggressive so you’d want it to be noticeably smaller. I wouldn’t do a kole and white tail together they’re quite similar and kole are more aggressive and the white tail is likely to be bullied.
Naso need 8 foot tanks minimum, IMO although I’ve kept smaller ones in 6 foot tanks for a few years and they don’t grow TOO fast. Powder blue is just a bad idea period, very aggressive (typically) and although it would be fine with your tankmates as I said, it needs a lot more length and space.
If you want an acanthurus tang, convict tangs stay pretty small and grow more slowly.
With all of this, you’d be best to quarantine as you’re asking for trouble otherwise.
The zebrasoma tangs would be more likely to get along in trios (how I’ve always kept them) — avoid Desjardini and sailfin tangs as they get too large and grow too quickly. Scopas, Yellow, purple, and black would be good to choose from. I’d advise against two of the same and of these species I’d say scopas play the worst with friends. Purple are often aggressive but in a community of several tangs they’re generally not bad, but I’d recommend a smaller one, 2-3.5 inches and the other tangs to be considerably larger.
One more thing to consider with species choices is that occasionally purple and kole won’t get along, not sure if it’s coloring or what. I’ve never had it be a long term issue as both tend not to hold permanent grudges amongst several other tangs. Acanthurus tangs like powder blue, powder brown, Achilles, and occasionally goldrim will hold permanent grudges and when they decide someone needs to go they’ll see it through and remember to attack them again months after being removed or “sumped”. Powder blue being the worst offenders.
Finally, I wouldn’t say they need to be added last, but I would say any angels, butterflies, or similarly shaped fish ought to already be present before the tangs. Wrasse, gobies, anthias, and most other species will be ignored by all but the most nasty tangs.
Algae eating blennies are often not tolerated, as they compete for food source. The tangs are likely to single it out and destroy it.
If you don’t keep many other fish, a trio of smaller zebrasoma and two bristlooth tangs might be OK, but you’d better skim heavy and monitor nutrients closely. Nothing is a guarantee but I do find overcrowding tangs leads to better outcomes for aggression, within reason. More than this and you’ll ask for trouble. 3 zebrasoma, a bristlooth, and a convict might work. 2 zebrasoma, two bristlooth, and a convict might work. Watch max sizes of your fish.
I’m saying this also because you plan to upgrade — if you don’t think you really will in a couple years, be prepared to rehome fish.
Thanks
