Like most kids his age, your little darling is also reading fluently. He is not just reading but is able to comprehend the meaning and purpose of the writing. With a memory bank of vocabulary and comprehension skills, you child is now able to handle a wide variety of texts. Books, newspapers, magazines, even pamphlets will interest him and he will love to practice his reading skills on everything that he would find lying around the house.
What you need to know
Right now your kid is reading for pleasure and not to gain knowledge. Let him choose the books based on his interest area. Do not try to force him to read the books that you think are apt for him and will increase his knowledge as it might push him away from books. Right now it is just important to inculcate the habit of reading even if it is just comics. Habits built at this time remain for life and reading is one of the best habits that you can encourage your child to have.