African clawed frogs, Xenopus laevis, are not very picky eaters, and will even consume non living items. They have been know to eat small, or chopped up earth worms, brine shrimp, or even things like chicken liver, or untreated ham. Probably one of the best foods for the pet keeper is a freeze dried food meant for Amphibians.
There is a dwarf type African Clawed Frog, but the bigger type gets to about 4 or 5 inches at adulthood. With good care, their life span in captivity could go between 15 and 20 years.