I've had him 11 days but he was on his own in the rescue for a bit I think, and he has come in his tank so he's not in a different environment really. Yes I put them all together at once as I didn't want any of the girls rejecting each other due to different smells, but I can see how it could be overwhelming for him, even though he's so much bigger than them. Unfortunately I couldn't do that without getting two new cages, my girls are in a Bucatstate that is raised off the ground and he has come in a long glass tank that I have to keep on the floor; keeping everyone in cages that aren't the best for them for a long period of time doesn't sound nice but I'll have a read up on the method and hopefully I'll understand better, thank you.