I got some sinking fish food wafers last year, and because the tadpoles liked them I finally got around to getting some more this year.
The wafers are intended for things like catfish and loaches, and I put them in a terracotta dish on a pond shelf- that way I can see if the food is being eaten or not. I was surprised that a newt was the first to find them- but it wasn't long before the tadpoles discovered their new treats as well.
I put out about a half-dozen wafers every day... and the tads seem to like basking in the empty dish until breakfast arrives. Hopefully the extra nutrition will do them good!