Well, the normal minimum is 50 gallons, and it grows out fully to be 8 inches, so i would think hard about how much space the fish will need once he's even 6 or 7 inches. Also, as BeanPets stated, they are very difficult to feed. Extremely shy, and you may need to try different foods to see which one it will eat.
Also, this is a very peaceful fish, so if you have any tankmates that my pick on him or stress him out, such as aggressive fish like damsels, then i do not think this fish should be placed in your tank. They also have been known to pick at coral, small invertebrates, and anemones. So just make sure you know the risks of owning one of these if you have any of the livestock i just mentioned.