If he's scrapping glass it could be his reflection is being a problem to him. If he was indeed a wild caught cham it will not be so easy to get him use to enclosure.. I would attempt to put him in a larger enclosure with lots of things to climb. Cage would be best. He may be trying to ward off his reflection.
Ahh, I see. He's getting himself up to the top and pressing his nose against the screen. There's nothing to hold onto up there so his feet scrape on the glass.... but ok, I bet I could rig up a bamboo siding so he can't see his reflection. Plus, that'd add to his feeling of security, I think.
He came to me in a 10 gallong aquarium, and I put him in a 30 gallon tall, filled it with plastic shrubbery and hidey spots and a big scraggly peice of driftwood. There's plenty of foliage.
I'll go out and buy him some more things tomorrow; but a new cage will have to wait until friday, unfortunately. After his vet visit, I'm going to be a little tapped.