Champion replied to somebody on another forum. I'll just post the link:
Did I expect to much of Champion Petfood? - Page 2
Their fish passes fit for human consumption (they say their ingredients are produced exclusively from animals fit for human consumption). It comes from these animals, but no longer would be considered that when reaching Champion (IMO). I've never seen where they have said that their products "are" fit. They always say something like "have passed" (as in, they were par of an animal that was, but may not be anymore).
They say they pull the remaining meat and fat off the carcass. It is this that they use. "a very high quality ingredient - the same fish that goes into human grade fish cakes". They think their meat/fat that is pulled off is a high quality ingredient (for dogs, it probably is). Then they say it is the same fish that goes into human fish cakes. Notice they didn't say it's the same "ingredient", but the same fish (do they mean type of fish)..? They also use bone which is also fine. But it sounds like what they are using would be called by-products if any other company used it...
I wonder if this Freashwater Fish Company sells minced fish or has a market for it. If they do (would have not need to render it), then that doesn't look good for Champion.
Anyway, this email didn't do anything for my suspicion. I hope somebody emails them again and asks more specific questions. Also, the terminology does get a bit weird with fish because less of it seems to be considered waste.