Casco Antiguo offers tacos filled with marinated halibut, typically served on house-made tortillas with bright toppings and a mint-forward mojo sauce.[7] The distinguishing feature is the use of marinated halibut in a Mexican taco format, blending Pacific Northwest fish with a herbaceous, slightly unconventional salsa compared to standard fish tacos.[7] Eating these tacos brings a mix of soft tortillas, tender pieces of halibut, and a fresh, aromatic sauce that adds herbal lift instead of heavy creaminess.[7] Editorial coverage of the restaurant points to these halibut tacos as one of the notable seafood options on the menu, especially for those seeking a lighter alternative to pork or beef fillings.[7]