If hes about 6 inches expect it to start soon. I had one but really really stupidly sold it because it was starting to be trouble.
It killed a convict that was 4"+ i woke up in middle of night and as i walked past tank spotted it carrying con around by the head. It was way to big for it to eat and it was floating around in the morning dead.
It used to lip lock with my bigger cichlids if they poked there head in his cave and it broke a small oscars jaw almost completely off one day.
It also ate numeruos small things.
They are very cool though and i really regret selling it now as they are very rare here. They are the sort of fish worth having there own tank if yours ends up needing it.