The image of a small boy bringing home a recently captured frog is a long-established part of Americana. What to do with the frog afterwards is less well-known. Most frogs can be kept in captivity in a large aquarium that has both land and water areas. Frogs are amphibians, which means they're born in water as tadpoles before maturing into land animals. Some varieties, like woodland frogs, only venture into the water to breed, then spend their lives in the surrounding forest. If you have a tree frog, be sure to provide it with something to climb on. Most frogs eat live insects, although some large bullfrogs have been known to gobble down mice. If you plan to keep a frog as a pet, consult an expert to determine which of the many species it is, then create an environment that matches its natural surroundings.