my boy ace is a total mush when I have him out of the cage but when hes in the cage and I put my finger by it he'll nip, and sometimes pretty hard. Any ideas why he'll try to bite through the cage but not when I have him out of it? Thanks!
Rats are very territorial...the cage is his. When you put your hand through the open door, it means scritches, food or coming out to play. When you put your fingers through the bars you are invading his territory.
Rats often huff and puff at other rats on top of their cage and bite at toes etc...just defending their turf.
Maybe he is grooming you and accidently did it too hard? My rat did the same thing and took a piece of my skin off. She is always very sweet. If you have always had him it's good you haven't fed him through the bars. That will cause unintentional biting. I think maybe it could be a territoral issue. My rat Ratty will push my fingers out of her Igloo. Hope it works out for you.