That is just plain disgusting.
Please don't misunderstand me, I'd eat the things if I were starving. But to mainly raise them on shit for food is terrible.
I have to say I've never eaten any, finding more familiar fish readily available. And now I hope I never will eat any. There should be some label requirement.
On the other hand, if the chickenshit were used to fertilize a grain and that grain were fed to the fish, I'd think that's OK.