After tadpoles grow four legs, they are biologically called "secondary adults". The food of tadpoles has also become animals, such as flies and mosquitoes. If you feed him food that "he" can't move, such as fish food, then he won't eat it and he will starve to death.

If a tadpole grows four legs, you should put the water in the pool shallow, very shallow, 2 cm is enough. Put some tiles and stones in the pool where water can come out and let them climb up and have a rest. Stay in the water all the time, they will suffocate.

That's how my tadpole died. I didn't know until I checked the book.

If released, it's best to put it in a temple, because it won't be taken away there again.