A puppy's stomach capacity at the 2.5 months is small and it needs to be fed at least 3 times a day. At around 5 months of age this could be reduced to twice a day. The amount of food to be given will vary depending on the puppy's size, weight activity and environment. You should not allow your puppy to become overweight. There are many branded puppy growth food available in the market and you might want to introduce them to your pup. In that case you would not need to provide any supplementation. Have fresh water available all the time.