Frogs eat any live fish that is small enough to fit into their mouths. Many pet frogs are content to eat guppies, minnows and goldfish of the appropriate size.
Frogs catch their prey by touching the prey animal with their sticky tongues and rolling their tongues quickly back into their mouths. Accordingly, wild frogs can eat anything that fits onto their tongues and into their mouths. Large species of frogs, such as the Khorat big-mouthed frog, often eat whole birds as do American bullfrogs. Others, such as pacman frogs, eat live mice and rats or even other amphibians and lizards.