I only speak from personal experience; Currently I have 5 tangs in my 155 gal. 6' Bowfront. Every now, and then they will do a little switch blade dance, but nothing alarming.
I never in the past 11 years attempted to add a single tang in to a tank that already housed other tangs, but it was do it or give up on having my PBT. I always added 3 at a time.
That worked OK because the attention/aggression got spread around vs a single tang getting all the attention/aggression from the other tangs.
I just added my last tang (powder blue tang) last week. Initially there was quite a bit of aggression from the smallish Yellow Tang [it is getting less & less], the other tangs (Purple, Hippo, and Sailfin tangs) did check him/her out let it know that they were there first, but no big deal. It did get a tear in it's dorsal fin the first night in the tank which has already repaired.
I AM NOT saying that you should do the above as this method NEVER worked in the past for me which is why I always introduced trios.
I attribute the success of the above PBT to a number of things: First, and most important is that the Powder Blue Tang I am speaking of is/was an extremely healthy specimen.
Second is it's personality, the fish I speak of is not easily intimidated. {Heck, I sort of wonder how aggressive will he be in the long run.}
Third is that I keep my animals well fed; meaning there is plenty of food to go around. Got to understand that due to my feeding habits I have to keep maintenance to a strict 20 to 30% weekly schedule, as well running gfo/gac, and a good Protein skimmer 24/7.
Now to a pair of Naso tangs: My best friend had a pair in her 155 gal. tank (for how long - I do not remember) which I inherited. They were beautiful, and always swam together. I loved that pair, they had some personality.
I could not go near the tank without them coming right to where I was. I lost them when we switched out the tank. I believe they were stressed to much. They were OK with the initial move from Lee's house to my house (Oct.,2006) but the second move from the 75 to 155 (Dec.,2006) and then to the new RR 155 (Feb.,2007) was just to much for them.
Naso's stress easily, and more often then not perish! With that said; IF I am ever blessed with a 220 or larger tank I would love nothing more then to have another pair of Blonde Naso Tangs. Not that I would hope to have them breed or anything like that.
The pic here show's the pair just before the third transfer to the new RR tank. Tank had been getting torn down hence it's state.
Great all around advice, thank you! I plan to add as much as I can to the tank on the same day... hopefully next weds
Be very careful on adding to much to the tank at one time. The bio-load could prove to be way more then your tank can handle, which could result in the death of the animals.
