What fish would you recommend for a beginner who wants an aquarium?

For a beginner tank, I'd recommend easy-to-care-for guppies. I'm not talking about the fancy varieties that are sensitive and require more care. I am referring to fish that don't need heat because it can be difficult for a beginner, let alone a child, to get the water temperatures just right. Guppies live about three years and don't take up a lot of room, especially if the males and females are kept separately. Also, if you do allow the fish to breed this gives your son the fun experience and responsibility of raising the young fry. To avoid having to keep a separate tank for the fry, you can simply add 'hides' to your tank, which means rocks, plants and little aquarium toys that the young fish can swim into to avoid predation. Quite often, if the adult fish are kept well fed enough, the fry will boldly swim out among them anyway. Feeder guppies are perfect for this little project as they can be colorful and fun to watch and still give your beginner fish enthusiast the experience he needs, without running to a serious expense.