Not all chams get territorial immediatly after they have hit 6 months. Some take longer to hit there growth spurt and/or get aggressive. Some may never get aggressive. If you try showing him a female then his reflection then there is a possibility he will fire up. Don't expect any luck though because it doesn't work on every cham.
lol i think people overstress on the whole "stress" debate....eh now and then its fine...even stimulating if you ask me....we try to make their evironement close to how it is BUT the one thing missing is what they are good at...."survival", insitncts,.....they just have a "safe: environment AND with a constant supply of food/water....in the wild they hunt, they see animals, they see other panthers....stress and stimulation.....to me if you constantly hold them is an issue but other than that...they are tough,, as far as panthers and veileds go...other chams i cant say...some are shy or pissy to begin with
if you want to see him fire up, try showing a female, or a picture of a fired up cham