The trout were probably doing just fine lurking in 50 F. plus water until someone decided if it it's not broken I still need to fix it.
Sounds to me like the thermocline got busted up it bringing water temps up and possibly some anoxic water on the very bottom. And of course warmer water does not hold as much oxygen so the trout were bunched up in the best place for oxygen.
I just hope it's reversible. The diffusers may have permanently ruined a good situation. 10 gpms of new water is not very much water for a 1/4 acre pond. If it was me I'd keep the darn compressor off until I accessed the situation!
