Hi, and welcome, Castor is so cute. We switched our two guys from puppy food to adult dogfood when they were 7 months old. A good age to to do this is at 6 or 7 months old, and at the same time, we reduced their feedings from 1 cup 3 times a day, to 1 cup feedings twice a day. We just eliminated the lunchtime feeding, and they were fine, you don't need to increase their feedings, as this may cause him to become overweight as he gets older. Our two guys are both 23 months old, and they both weigh 45 lbs. my vet says she would like to see them weigh 40 lbs, as it's better for their joints. If you find that Castor needs more food, you can add "extras" to his kibble such as green beans, cooked carrots, broccoli, or cauliflower. We add one of these to their evening kibble, and we add 2 Tbsp. of plain unsweetened yogurt to their morning kibble. Yogurt is an excellent source of probiotics, which is great for digestion, and it also boosts the Immune system.