When frogs are babies, they are called tadpoles and they live and breathe in the water just like fish do.


Source
http://www.google.com/imgres?q=tadpoles&um=1&hl=en&client=firefox-a&sa=N&rls=org.mozilla:en-US:official&biw=1165&bih=606&tbm=isch&tbnid=7e4_PZytEt5doM:&imgrefurl=http://www.bettyhallphotography.com/blog/2010/03/tadpoles-and-polliwogs/&docid=fX2VNUXe5FdIwM&w=450&h=300&ei=2a5yTtOhK8PI0AG367CBCg&zoom=1&iact=hc&vpx=576&vpy=212&dur=549&hovh=183&hovw=275&tx=127&ty=100&page=3&tbnh=121&tbnw=160&start=28&ndsp=18&ved=1t:429,r:9,s:28