Ask that question in the wildlife/marine-life section
How To Tell What Breed Your Tadpole Is?
Ask the pet store usually they have a amphibian person who knows everything you can bring em in and WALLA!! You know everything about your little friends. They might even be different species all in one container if you just scoop em out randomly from a pond (thats what I did ;) )
I would ask that question at a local pet store or go to ask.com