I know it seems like it would be a lot for him to eat, but judging from your pics I see no problem with him eating a large adult mouse/weaned rat. You want his meal to leave a noticeable lump in his stomach after he eats. Most of us feed on a 5 day schedule for younger balls, which yours appears to be. Once they are a little older (some say 500g, some say a year old, etc) they usually move them on to a 7 day schedule.