I took my ig to the vet and they tried to get me to nuder him. They say males can be very aggressive. I didn't fix him though and mine is very aggressive. Could be his housing maybe? They say iguanas are very intelligent and like something to look at. Maybe hes getting bored. Try moving him by a window and get a bird feeder to give him some entertainment. My igs demeanor changed instantly just by moving him by a window.