I have seen the black fly use of unwanted fish and a thread growing monsters with trout pieces. What about grinding or blending fish to feed the forage? I usually just feed the YOY BH to whatever opportunistic shore critter that happens by the pile while I'm gone. Rarely nothing eats them and if so they get pitched into the pond.
Would it be a better use of protein to grind them up and dumped into the pond? I'm currently just pitching BH heads, etc back into the pond which surely only feed the turtles.

No idea, not sure what eats ground up fish. Might be an interesting controlled experiment for a large aquarium that would allow you to actually see the results. If they didn’t eat it, you would probably have some fouled water.

I doubt that, in small amounts, it would have any type of negative effect on water quality.

Baby RES like ground up fish. I used it last summer to get a batch of them started on pellets.

They were caged, but I expect pretty much any sunfish would gorge on the stuff if it was fresh when they found it.

The crayfish and turtles will clean up whatever the fish don't finish.