how do 450 fish die in 12 hrs??

so i walked in to work today and noticed all the cardinal tetras and neon's were dead then i glanced to the right and noticed all the african cichlids were dead as well, all the balas, and the molly's guppys and community were all at the top, yet all the rainbows sunburst plattys ballons catfish all at the bottom lots of mixed feelings we ran numerous test water temp's every kind of test you can imagine and everything was ok??WTF.

oyeah and in my own personal experience angel fish are the first to go if somethings wrong with the water, but the ones in the store are fine and all40 tanks are runed by the same giant sump?

they are all 20 gallons, and yes i suspect someone f*&%$d with the tank

DAMN!! that just might be nothing else makes sense!! thank you mr nunez!!

that was a knee slapper ryan!!how old are you 12!