Why did the guy at the pet store say a 40 gallon is fine, but everyone else says different?
Pet store workers get commission, which means they’ll often say anything to make a quick buck, whether it’s right or wrong – this is not necessarily true for all stores, but seems to be the general trend. A 40 gallon enclosure is too small and will slowly kill your uromastyx. An enclosure of this size is only acceptable for a couple of weeks until you have finished building or buying a bigger enclosure, although a sensible owner would have this sorted before buying the lizard.