He's old enough to be an adult. From my experience, they start to slow down to feeding every other day about 10 crickets around 7 months old. If he's eating every other day, not losing weight, and active, then I wouldn't worry. =] Feed him whatever he'll eat. Also know that the colder it gets, the less he'll eat. Around Nov mine stop eating every other day and go to once a week, then for six weeks they don't eat all together. It's called Brumation.