Pondering that point.
I have no doubt what you say is true. None at all. And there's an interesting side note.
Chicken and pig manure are highly valued as fertilizers. Therefore to feed it to fish presupposes that fish are more efficient at converting them to human food than plants are. And that the financial gains are better feeding fish than plants.
Kind of interesting. Still disgusting.
By the way, one of the more valued organic fertilizers in the US is ground-up chicken feathers. Yep, just the feathers, ground up to a fine powder.