Please don't misunderstand this to mean that I'm casting blame on TFF!
OK. That's easy enough

I have no idea who did the stocking.
That's why its so easy.
But if whoever did this cannot tell the difference between CC and bullhead, they should be in another line of business. Gross incompetence or maybe even dishonesty.
That's why I think that the inference is ridiculous. Just don't think it happened as you imagined it did. I know several members who have Bullheads in the their ponds. I don't think any of them got there as a CC stocking. I could even list the names of the suppliers, but I wont. But this much I know, some would be defended while others would not.
I don't understand why you didn't just ask the developer to show evidence of the stocking. You know like with a receipt or something like that. But you did a survey at your expense. Sounds to me like you didn't trust the developer and if you didn't why are you letting him completely off the hook about "Gross incompetence or maybe even dishonesty". Though I think the facts are true ... I am rather skeptical of the extrapolations and opinions.