I unfortunately lost my fish several years ago - lost 7-8 lb bass and 15 lb catfish - only fish left alive were small perch and a few small bass - it is quite a blow if a die off strikes your pond. Mine was in late September, lots of heat and drought conditions where the pond water level had dropped. A cool rain hit one night, filled the pond up quickly and turned over all of the dead grass, weeds, etc. from the drought. Arrived next morning to finds hundreds of my fish either dead or gasping for oxygen. Thought at first they were poisioned but not the case - In most ponds aeration can potentially save much money and years of effort - starting over from scratch is no fun.