While fishing yesterday in Brookville I witnessed the thickest hatch I have ever seen.  Looked like a grannom.  Would that sound correct?  The hatch was so ridiculous I can't describe it, but few(and I mean few)fish were feeding on the surface. Can anyone explain?  I have my own theory, but want to hear an educated one...lol.

my gues would be they were feeding, just not on the surface, eating the caddis as they swim through the water column, before they reached the surface.

or

There aren't any fish where you were.

I have seen this before on fly projects where I know there are fish.  So many bugs coming off that the fish can feed under without any effort.