I do this for my ig and my tegus. I love animals, but having poo everywhere is not my cuppa. The tegus will poo in their cage anyway, but will also poo in water. The ig will hold it until I put him in the tub...days if necessary. I don't know if that's considered potty training, but it's going to make going on vacation a lot harder :O You can try providing a large tub of water in the bottom of the cage to see if he'll go in there.