Freedomeagle, glad the vets had fun!
Didn't you have some weird water chemistry last year? I thought you speculated that several big rains may have brought detritus into your pond.
Perhaps some of what came in last year fertilized your pond? If so, then the trout obviously feasted on something that came up from your enhanced primary producers!
If that is the case (wild speculation), then maybe you should look at some more "conventional" fertilization next year?
