Fish is fish

Fish and tadpole grow up in a pond together but when tadpole begins to grow and change, their relationship changes.
I have read this book many times and I love it every time. The themes in it are so teachable: the changes that come with growing up, how friends can grow apart, how to deal with jealousy, etc. I taught this in Summer 2011 and it was over the first graders' heads a bit. I'd like to try it again.