Everything I’ve ever heard about raising tadpoles has been keeping track of water quality and not feeding them too much… XD Hopefully one of my followers can give you better advice haha
That’s it. Feed them tadpole food or betta (high-protein) food and plenty of veggies and greens, frozen first to make them soft and easy to nibble. Keep the water clean, and give them places they can lean on to have their faces out of the water as they start to grow legs. When the legs get bigger, make sure they can climb out of the water. A sponge filter is good but not mandatory if you keep up on water changes. They shouldn’t need a heater. Throwing some fallen leaves into the tank will grow bacteria and algae for the tads to eat.
For tiny tadpoles like most toads, you can keep several of them per gallon. For larger tadpoles like bullfrogs or leopards, at least 1 gallon per tad, preferably more. Keep an eye on them, they occasionally become cannibalistic, especially if crowded or low on protein.
When they have all four limbs and are absorbing the tail, they don’t eat. As soon as they’re frogs/toads and that tail is totally gone, they need to eat. You can either give them flightless fruit flies or other small bugs, or release them. Be sure to release them very close to where you collected them.
If you buy a tadpole rather than collecting it, it’s yours. Releasing it risks spreading pathogens, so you better be set up to care for a frog.