Tadpoles eat a wide variety of things. It ranges from species to species. In the wild most tadpoles will eat micro plants and algae. Some species are omnivores and eat organic debris from decomposed plants or animals.
In captivity they can eat a wide variety of food. For example baby food, egg yolk, and lettuce. If you are raising tadpoles your choices will vary for different types of tadpoles. Some popular things to feed them are lettuce and spinach.
Before hatching Tadpoles eat thier own yolk sacks. A fews days after hatching their gills start to develope and they becomes vegetarian. When the tadpoles back legs start to develope or soon after all tadpoles become carnivores. They will eat insects, larve, and other insects or small anaimals in the water. If they do not get enough meat to eat they will eat other tadpoles.
Frogs and toads lay thousands of eggs covered with a jelly-like substance that helps protect them from being eaten by other small creatures in the water. These eggs clump together and float to the top of the water. This is kownn as a frog-spawn.
After a few days tadpoles with hatch. Tadpoles live and swim under water. After about a month their hind legs will start to grow as well as their lungs for breathing. After a few months their front legs start to grow and their tails will dissapear.
If you want to have pet tadpoles you will need to fill a large container or fish bowl halfway up with chlorine free water. If using tap water let it set for at least a week in the sunlight to get rid of any chlorine or chemicals used to treat the water. Do not put the tadpoles in direct sunlight and replace dirty water on a regular basis.
You can feed your tadpoles boiled lettuce or cabbage. Chop it up and freeze it so it does not go bad. Give them just a pinch every few days. If you give them too much it will pollute the water.
Put in some stones, branches, or leaves so there si a surface level for the tadpoles once they develop legs.
When they start growing legs feed them meat such as live bloodworms. They will be too small to eat crickets at this stage.
Frogs are carnivores and eat live prey such as insects, snails, spiders, worms and small fish. Some of the bigger species of frogs will even eat small mammals like rats and small reptiles like lizards. Some frogs have a long sticky tongue they use to grab flying insects like fruit flies.
If you have a pet frog some popular things to feed them are crickets, moths, flies, and worms. Sometimes they will find their own food by eating fruit flies, houseflies, moths and other insects that happent to buzz by. They can survive about two days without food.

A What Do They Eat? project.