Which Tang would I be best off getting?

Base on the decription of your tank, and choices. I would rule out all of those tangs. Firstly, a Sohal would do better in a 6ft tank for more swimming space. Sohal are very agressive and territorial (could be a mean bastards). He will not let your hippo be in Peace! In my experience Tangs do better in odd numbers. As for a Power Blue Tang, they also can get territorial as well. As for Achilles, not an easy fish, they are very difficult fish to keep. These fish are too big for your tank, as mention from other members here.

Note: It's always best to get tangs in different shapes and totally different in colors. If there is a similiar like in each other, they will go to war! Someone mention a Yellow Tang, that would be an excellent choice.

Remember to get your next Tang small, because eventuall they will grow out of your tank. Good luck in your search.

 

+10000 to this.


I believe some tangs will go after other fish (not even just tangs) of similar shape.

Our tomini tang and flame angel battled for the first week or two after adding the flame. I believe their similar shapes had something to do with this aggression. There were only three fish in a 120 tank at that time; 5" tomini tang, sixline wrasse and then the 3 1/2" or so flame angel.

Hopefully all of this information is compelling the OP to reconsider the original three tangs.

There are others out there which would fare far better in that sized system.

 

forgot to mention that I will be getting a doctorates in physical therapy in 4 years and one of the first things I am buying is a larger tank.

 

A lot can happen in four years... but if you mean by this that you can find a tank for a tang you buy now, then I don't believe that's a good strategy. I believe the tangs you mentioned (besides the PB) will outgrow your tank faster than you think.

I have a powder blue in my 120 gallon, but it is a 5' tank, so there is plenty of swimming room and some "islands" of rock to swim around and keep it occupied... it is also the largest fish in my tank now once it outgrew my yellow dwarf angel... they are awesome fish, but it can be very difficult to find a good healthy one, which is why I would caution against them. While I had always wanted a PB Tang, mine was eating voraciously in the store, which strongly influenced my decision to purchase it. It now eats pellets, and is thick and healthy.

 

fwiw, I have a sohal in my 180 and many times it seems too small for him. this is an almost 10" fish. beautiful but BIG. they can become quite agressive. mine has been very well behaved. I want to add in either a Powder blue or Achilles, but still undecided if I will do so. when I added my purple, it was the purple that caused the aggression and not the sohal. he just stood his ground and with a scalpel of almost 1/2", put a nice wound on the purple.