Chameleons are also very territorial. Males housed in the same cage may fight, or the more aggressive chameleon may assert his dominance in more subtle ways, keeping the subordinate one away from food and water. Male lizards should never be housed together, if at all possible. Lizards should also not be kept in highly reflective stainless steel cages, and mirrors should not be placed near their environments, because males may display to their reflection, resulting in additional stress. Crowding will exacerbate stress, and usually the more dominant and aggressive lizards will feed, while the others will slowly fail to thrive.
Geckos are an exception regarding housing.
It is common practice to house a group of females with one male, for purposes of breeding. But, it is still bad to house more than one male per enclosure. Water turtles may successfully be housed together, if they are all close to the same size and observation shows that a few aren't nipping at the others. Box turtles and tortoises can often be housed in groups of similar species. If several are kept together, the cage should be as large as possible.