John, if I get up and jog around the block a few times I'll be in better shape, but with your philosophy, I'm better of staying home so I don't get hit by a truck.
My guess is the Amerinds used dead fish "leftovers" because they had it, and rather than throw it away, put it to use, to add organic matter to the soil. I doubt they would spend the day fishing and then throw the whole fish away.
What the hell is my point? Amerinds had extra fish guts, we have cow droppings. Compare the price per pound of cow manure to fish emulsion, then tell me which product would improve the soil structure and fertility better, for your dollar.
Now, on chlorotic oaks, you and I live in southeastern Wisconsin, which sits on a limestone bedrock and we have typically HIGH soil pH. Every homeowner thinks their oak is chlorotic because of it, but you and I know it's because of what they did to the root zone, change grade, trench, rototill, add septic, compact, ect.
I visit a site with chlorotic oaks (typically white oak, pin oaks do fine here and they are the one's that like acid soils) and see root damage. I can make them green by drilling the trunk and injecting iron, dumping nitrogen, or squirting fish guts on them(your method of choice), but the underlying problem is root damage.
What might be better for the tree is to reduce stresses and slowly improve soil structure. One could do a soil test to see if there are deficancies and correct those, water during times of drought, control pests, aerate soil, modestly apply organic matter in the root area, carefully remove plants that compete with the tree(buckthorne, grass, hostas, ect.), and for the trees sake don't remove ANY live branches, yes, even suckers and even lower branches.