Atlantic cod (Gadus morhua) is a widely consumed and commercially important fish species, valued for its mild flavor and flaky white flesh. Despite its familiarity, many consumers wonder if this popular fish has scales, as its skin often appears smooth. This query arises because most people only encounter the fish after it has been processed.
The Definitive Answer: Scales on Cod
Cod fish absolutely possess scales and are fully classified as a scaled fish. The widespread belief that cod is scaleless stems from commercial handling practices.
Cod scales are exceptionally thin, small, and not deeply affixed to the skin’s surface. Consequently, the scales are often sloughed off during the rough process of netting, handling, and initial washing at sea. This natural shedding means that by the time the fish reaches the market, it frequently appears bare of scales, giving the skin a smooth texture.
The Unique Structure of Cod Scales
The easy detachment of cod scales is due to the specific type of integument they possess, known as cycloid scales. These scales are characteristic of many soft-finned bony fish and are composed of a thin, flexible layer of bone-like material and collagen. Cycloid scales are smooth, rounded, and overlapping, which contributes to the fish’s hydrodynamic efficiency.
Unlike ctenoid scales, which are firmly anchored by microscopic, comb-like teeth, cycloid scales lack this spiny attachment. They are embedded in the dermis with a smooth posterior margin, making them less resilient to friction or physical stress. When a cod is handled, the slightest abrasion can cause these delicate plates to detach easily. This structure causes the fish’s skin to feel smooth, despite being covered in scales.
Culinary and Religious Implications
The minute size and loose attachment of cod scales have direct implications in the kitchen. Mechanically scaling cod is often impractical because the process is tedious and can damage the delicate flesh beneath the skin. Many cooks bypass scaling entirely, opting instead to remove the skin from the fillet before cooking.
For those who cook a whole cod, the small scales are sometimes left on because they crisp up when fried or grilled, acting as a protective layer for the meat. The presence of these scales also satisfies specific religious dietary laws. Jewish kashrut and certain schools of Islamic law require a fish to possess both fins and scales that are easily removable to be considered kosher or halal. Since the cod’s cycloid scales meet this requirement, the fish is recognized as a permissible option.