We are sincerely sorry that this happened with our fresh flight fish. We contacted our meat director and he was able to share this information with us:
"Unfortunately it is inherent in this species and it does happen from time to time as you have noted. As a preventative measure, our supplier has a candling procedure in place and they do check each fillet, but even with the best process a worm can get past just due to the nature of the product. The last line of defense is the merchandiser (us) and our teams check our fillets front and back for any visible worms- this is a visual check as we do not have a candling light, therefore it is possible that some will not be detected. It’s important to note it is not a health risk, more of a nuisance and is benign after the cooking process. Regardless, we don’t expect any guest to consume this and realize it is quite unappealing. At Festival we do pride ourselves on the freshest seafood’s and meats in Wisconsin"