i feed every thursday...every 7 day feedings..could it be the rat fills them up more than the mice do..they are roughly the same size. mice were 40 grams and the baby rats are 50 grams.. is that a big difference...

that occured to me today about the weight difference...he has been in same cage for 2 months now no issues.. hides, water dish, temps hot and cool side, humidity... nothing has changed..

thank you for all replies, any other ideas.. please