Trying To Identify this Fish
It looks like a unicornfish (genus Naso), maybe Naso vlamingii, the Bignose Unicornfish. They're Acanthurids, related to surgeonfishes and tangs. 

These are mainly found in Indo-Pacific ocean around the depth of 50 mts from surface. Coral reefs are their main habitat and destruction of coral reefs is their current biggest threat alongside trading by fisheries. A good source of information for this species is available here.

A copy of this fish. 



Picture credits: UM Rosenstiel School