"Seafood cocktails originated in the 19th century in the United States, usually made with oyster or shrimp, and seafood with spiced, cold sauces were a well-established part of the 20th century culinary repertoire. While cocktail sauce is most associated with the prawn cocktail, it can be served with any shellfish."

Notice that says Shellfish...

"In Australia, it is often provided in fish and chip shops."

Must have a bunch of Aussies on here.