Losing fish

[WHEELPOWER]

I'm losing ALL my fish and a few inverts. (Naso Tang, Pearly Jawfish & Bluejaw Trigger) They act like they can't breathe and semi paraylzed. There isn't any visual causes to the fish either. They all were eating one day and dead or almost dead the next day. All my corals seem to be unaffected. The water parameters are within ranges. Does anyone have any suggestions as to what is causing this?

Thanks,

Phil