IMO they need at least a 6 foot tank and just remember that a fish that big produces a lot of waste so you will have to manage that. I currently have mine in the 190g with a Moorish Idol, Gold stripe Maroon, 2 small Helfichi firefish, a Conspic Angel and a fast growing goldflake angel. I think my tank is overloaded at this point and am going to be setting up a 300g soon to house a couple of them (still undecided as yet who is going to get evicted). You have to decide if your tank can handle a fish that big with the other fish you are planning to add. I love my Naso tang - he is a gentle giant although definately the BOSS of the tank. He eats out of my hand - or rather tries to tear the Nori out of my hand as I am putting it in the tank - unlike the conspic that just goes straight for my hand and bites it!
