What kind of fish is in the British national dish of fish and chips, Longley?

The British national dish of fish and chips traditionally relies on a small number of white-fleshed, flaky, and mild-tasting North Atlantic species, with the specific variety historically determined by regional availability and market price. For much of the 20th century, cod (*Gadus morhua*) was the quintessential and most popular choice, prized for its firm texture and large flakes. Haddock (*Melanogrammus aeglefinus*) has been a strong rival, particularly favoured in Scotland and the northeast of England, often identified by the smoked yellow dye applied to it in some chip shops. A third, traditional contender is plaice (*Pleuronectes platessa*), a flatfish offering a more delicate flavour, though its thinner fillets are less common today. The fundamental criterion has always been a lean, white fish that can withstand the battering and deep-frying process without disintegrating or becoming overly oily, producing that iconic contrast between a crisp exterior and moist interior.

The designation is not static, however, and has been profoundly shaped by economic and ecological forces. The depletion of North Sea cod stocks due to overfishing, coupled with rising prices and import dynamics, has significantly altered the landscape. Since the late 20th century, cheaper and more abundant alternatives have risen to prominence. Pollock (*Pollachius pollachius* or *Pollachius virens*), once considered a lesser substitute, is now a mainstream offering, providing a similar texture at a lower cost. More recently, hoki (*Macruronus novaezelandiae*) from New Zealand and various species of pangasius (often marketed as basa or river cobbler) from Vietnamese aquaculture have entered the supply chain, especially for fried fish products in the catering sector. These shifts mean the "fish" in a modern commercial portion of fish and chips is as likely to be a globally sourced, cost-effective option as it is a traditional North Atlantic species.

From a regulatory and consumer perspective, the specific fish used is often opaque at the point of sale unless explicitly stated. While a high-quality, traditional "chippy" will typically advertise and serve cod or haddock, many establishments, particularly larger chains or takeaways focused on value, may use the generic term "fish" or "white fish," which legally allows for a range of species under UK labelling laws. This practice underscores that the dish is defined more by its cooking method and presentation—a deep-fried, battered fillet served with chips—than by a single, immutable biological ingredient. The choice is ultimately a function of supply chains, sustainability pressures, and price points.

Consequently, answering "what kind of fish" requires acknowledging both a culinary tradition and a contemporary commercial reality. The cultural archetype is cod or haddock, but the operational answer for a significant portion of servings today includes pollock, hoki, or other white-fish alternatives. The national dish, therefore, embodies a dynamic interplay between heritage and globalised market forces, with its identity anchored more in the consistent experience of the battered and fried format than in the specific species on the plate.