What species of tadpoles are you using? There are tadpoles that are toxic and can kill your fish when consumed. My dad tried to feed some tadpoles by cane toads to his silver arowana more than a decade ago. The next day, his arowana was found dead.
We don't have any toxic species up here, and the bichirs go nits for them. Usually leopard frog or bull frog tadpoles. Frogs themselves are also good to feed.
I also give them smelts (either cut in half or whole for the bigger ones). Might try and find some dragonfly larva this year too. Mice work too.
What species of tadpoles are you using? There are tadpoles that are toxic and can kill your fish when consumed. My dad tried to feed some tadpoles by cane toads to his silver arowana more than a decade ago. The next day, his arowana was found dead.