It's very hard, I believe, to keep tadpoles that turn into frogs, alive. Atleast that is what someone told me. I had an aquarium fill once of tadpoles (like, A LOT of them). Most of them died shortly after being in full frog form, so I started taking them back to the pond which I got them from as they became frogs. It's amazing to watch them change though! I got mine from swap like water..they need stuff in that water to eat or live off..like algie?