Thanks to the wonderful advise petco gave me my guy was a little bit under weight for being about two years old. Once I switched to rats and gave him proper sized meals his weight started to shoot up (petco said adult mice are good and feed two, then got more involved here and learned small rats were what I should have been feeding) so in my non expert/ learning opinion id agree he's a little thin but if anything like mine hell start putting weight on fast once you start trying to add weight. What's he eatting right now mice or smaller rats?