There are also street snacks called 붕어빵, but they're just in the shape of fish, no fish taste. Sometimes they're called 잉어빵 to sound fancier.
And while I'm here you can also say 붕어빵이네 which is like saying "they look so much alike." usually for a mom and daughter or something like that.
In keeping with so many other bizarre DL sentences, this could also be translated, "This evening I'm a goldfish." Maybe it's a costume party.
Could it be that this is supposed to be "carp"? I've only ever heard "goldfish" used to refer to the pet.