A 20inch vlmangii tang would die from stress in a 180 ''It gets about 20+ inches long and about 1ft height. Freshwater fish that size would handle it. Saltwater fish couldnt. The stress and waste level wouldnt mix well in just a 180. A full size vlmangii needs atleast a 10ft long tank . You can keep one in a 180 for awhile until it reaches about 10 to 11inches. After that a 10ft+ long tank is a must. They need atleast a 500 to 1000g tank full size. No disrespect when I say this but you should really study your fish more. If the guy next door to you likes to smoke crack and his neighbor smokes crack are you going to tell someone else its okay to smoke crack because 2 other people you know are doing it?Same principal. Just because 2 other people are doing it dont make it okay. overly large marine fish do not belong in cramped enviroments. a 180g tank can house a Red Sea Purple, a Regal/Hepatus/ A Hawaiian Yellow and a few other smaller tangs'' not all together but in general. Oh the Kole is a great fish for even a 120. It stays around 6 inches full size.