The below profile is on another one of the interesting tangs that I have kept.  This  information Powder brown Tangs is based on what I have learned and observed.

Common Name: Powder Brown Tang
Scientific Name: Acanthurus Japonicus
Reef Safe: Yes
Temperament: Peaceful for the most part
Care Level: Moderate
Max Size: 8 inches (around 6 inches is more common)

Appearance:

The powder brown tang has the typical oval shaped body, just as with most other tangs.  As the common name suggests, it has brown coloring on its body. There are white marks on both cheeks as well as near the eyes and mouth. The fins are typically a darker shade of brown when compared to the brown on the body.  The fins will also have a lighter blue colored highlights around the edges. The tail fin  will have a little different coloring having a strong blue undertone to it as well as a yellow vertical bar. There will also be a yellow strip along the body separating the body and fins.

Environment and Temperament

Powder brown tangs can become semi-aggressive when kept with other tangs of a similar shape, size, and color to them and can also become aggressive with other powder brown tangs in the same aquarium.  This behavior can actually be fairly common with most tangs.  The powder brown tang however is a great fish for a community tank as they will peacefully co-exist with any other types of fish.  They are also completely reef safe.

The Powder brown tang would to best in a tank size of 75 to 90 gallons or more. The reason for that recommendation is not only based on their average adult size of around 6 inches (give or take), but on their typical behavior as well.  They are a very active fish requiring a lot of open swimming space in the tank.   This makes the powder brown tang a very entertaining fish to have in a properly sized set-up.

The Powder brown tang will require suitable hiding spots so they can claim one as their own.  It is typical for a Powder brown tang to find a spot they can hide in among the aquarium live rock and go there whenever they get spooked, scared, or stressed.  The Powder brown tang really needs this “safe spot” to go to or they can become even more stressed reducing the effectiveness of their immune system and making them more susceptible to disease or parasites.  

Recommended water conditions / parameters:

I would refer you to the below article for the typical water conditions that powder brown tangs will do best in:

https://www.reefaquarium.com/2013/the-basics-of-marine-aquarium-water-parameters/

Diet

As with most tangs, the powder brown tang will accept almost any food you may offer it.  However, they are herbivores and will require a diet consisting mostly of sea algaes with some other verities of food on occasion.  A good quality flake or pellet food meant for marine herbivores is also a good option for the Powder brown tang’s main diet.

A reference for your consideration

https://www.reefaquarium.com/2013/responsible-fish-keeping/