Niles are absolutly one of the worst monitors to buy, they are general very aggressive and bad tempered. I don't recommesd a Bosc/ savanna or white or black throut monitor both can be a handful and both get huge. If this is your first monitor I totally, hole heartedly recommend an ackie, they are small and great lizards. If you must get a big lizard get an Argentina white and black tegu, they generally have far better personallitys then both savs and niles.