Absolutely adorable! I <3 me some ratties! Got 3 of my own right now (2 'naked' ladies and 1 remaining old fat male, sitting 'pretty' at 3.5 years old)

Wow 3.5 years! That's amazing :)
I have five myself, I hope they all get to that age :)

He's a little fighter. Oddly enough, when he and his brothers (I'd had him and 2 of his brothers, the only males from their litter) we figured this old guy, Placido, would be the first to go. He was the only one with health problems (a tooth abscess though, no tumors), but he's outlived both of his brothers and still relatively active, for as active as an eldery fat rat would be hehe. He's not much interested in us anymore, unless we have goodies, but he's otherwise still healthy. Our hairless females are only about a year and a half old. I hope they get to be as old as Placido too hehe.