Those in the US south should beware of tadpoles....we have a Bufo Marinus toad that is highly poisonous to fish in both egg, tadpole & adult forms (the youngsters resemble frogs until they get about 1"). My buddy who's the manager @ Old World Exotics in S. Florida has to have his guys go on 'Toad Patrol' every morning to prevent them from laying in the outdoor ponds & killing 1000's of dollars worth of fish stock.
The little green treefrogs (peepers), on the other hand, are quite tasty. I'll also drop in those big horse flies that bite the livin' hell outta ya...just for karmic revenge.