Hey and breakfast lots of fibre there Cheerios or similar with a bit of Yoghort.
If he likes cheese grate some up in his rice and a few small peas or similar veg,If he likes yoghort pop some blueberries or other fruit in it, how about one of the Delicious flavored Milks out there,Orange juice today has a lot of Vitamins in it,forget the iron it does make them constipated, Have you tried Fish sticks and let him pick them up,kids do go through the picky stage, back off a bit, say nothing ,let him sit with his food and just get on with what you are doing, make it less of an issue, sometimes they know Mom is concerned and its lovely to have more attention. Make sure he gets enough activitys to get his appetite up.Ton of books out there and the internet with Delicious foods to tempt them.