Reintroducing a Trigger

[hawk]

I removed a Naso after he relentlessly took after a new female Crosshatch. The naso was always peaceful prior. I wasn't sure if I should reintroduce him or not. After 3 months of solitary in the sump I put him back a couple of weeks ago. He has been great since. I never changed the aquascape but it might be helpful. How big is the tank and how long has the niger been out of dt?