Does anyone know anything about Iguanas?

You have to make sure his temperature in the cage is just right because that can affect his eating habits greatly. Look up the temperature it is supposed to be at and make sure it stays there. If this does not work it could be his digestive tract......if this is the case run a bath with lukewarm water about only 1-2 inches high (you dont wanna drown him) and this helps his digestive tract and he may poop.