First, I would hardly say most pet stores house their chams correctly either because they don't know how or they are not willing to give individual animals the space and security they need. They expect the stock to move...and by the time problems show up the animal belongs to a customer. Small babies can be housed together but only until weaker or more dominant individuals start showing up in the group. Keeping adults together usually means a greenhouse or room sized setup. Part of the problem is individual personalities of chams. In any group one is bound to become the aggressor, and if the others can't escape to habitat that gives them security as well as proper temp, humidity, light, food and water, the less dominant chams will start showing health problems. Some melleri can live in small groups as well as fischeri, but if you aren't lucky enough to have chams that get along you'd have to separate them regardless. Also, gravid females should be separated anyway, so separate caging would be needed at some point.