OMG, Savannah, that is HORRIBLE! I am sitting here with my mouth open, aghast. How on earth can someone do that?
Those firemen (many of whom are medics sworn to PROTECT life) must have been really drunked-up, as that act had to have gone on for quite a while, to catch that number of fish in a sizeable pond, and then go after the lilies. You know they had to know those things were valuable, too, because you can't mistake a koi for a bluegill.
I agree - report it to the FD. You might also alert the mayor. After all, the FD is a city entity, and even if it wasn't firemen, it was their event that brought the trouble makers and the raucous behavior.