Hi!! it turns out that i used the scales wrong last night (duh) so tobasco actually weighs 180g, 17mnths and is on 2 mice every 7 days. how is this??????
The advice you have been given is right Meg, as long as the medium mice are not more than 1.5 times the width of Tobasco's width at his widest point (which I very much doubt they will be !!).
The mediums I have been feeding Silvesta weigh around 20g....although they differ a lot!!
The reason for moving him on from 2 small mice to 1 medium is that at the moment he is having double the amount of calcium that he needs....so it is better to move him up to a single feed item, and also good to start stretching his jaws and getting him putting on more weight so he can then slowly move up from mediums to large....