1)Originally from Asia.
2) Get large.
3) Introduced lots of places, including here.
4) Edible, hence 3.
4) During spawning, skitter through shallow water like torpedoes and ram canoeists, who then beach canoe, run panic-stricken to nearby nature house and claim to have been attacked by lake monster. (Really.)
5) Drop bird seed in water, frenzy ensues.