So I defrosted the rat in the fridge overnight. Today I put the plastic bag under very warm water for a few minutes to get it warmed up. I went to put it in his tank and accidentally dropped it. Before I could pick it back up, he attacked it and decided he wanted to gnaw on it for a few minutes. Gnawed on its middle and then its feet. I got the feeling it was way too big for him. He let go and I picked it up with the tongs and started the rat dance. He looked uninterested for five minutes. Finally he took it. For the first 5 minutes, it really looked like it was way too big for him to take down. Everytime he seemed to get the his head over its head he would back off. But he is an eater for sure (2 weeks ago a live mouse at the store before I took him home, 5 days ago a F/T mouse no problems and now onto rats) so he kept trying and eventually took it down. He is fat and happy in his hide as I type! Here are some pics: