No.... once the unicorn tang matured, horn will definately grow out(especially males) only if yours is the species which horn can developed cos lots of naso juv look very alike and you may got one that may not have horn development..... the one in the pic is a naso vlamingii, a deep water naso tang and will have big nose growinf instead of a horn growing when matured......
Adult look like this, swee bo(my favourite naso tang species)