A category name covering several unrelated white fish, most often the European sea bass (branzino) or the Chilean sea bass, prized for mild, sweet flavor and flaky (or, for Chilean sea bass, buttery) flesh.
European sea bass is native to the Mediterranean and northeastern Atlantic, with a slender body and firm white flesh; it's a staple of Italian, Greek, and Spanish cooking, usually grilled, baked, or pan-seared simply to showcase its delicate flavor. Chilean sea bass is not a bass at all — it's the Patagonian toothfish, found in the cold Southern Ocean around Chile and other sub-Antarctic waters, marketed under its more appealing name since the late 1970s; it has a rich, buttery flavor and dense, flaky texture suited to baking, grilling, and searing, and is popular in upscale restaurants and sushi bars. Both are versatile and can be baked, grilled, pan-seared, poached, or fried; European sea bass appears in French bouillabaisse, while Chilean sea bass is a major part of Chile's fishing economy. Sea bass is delicate and perishable, so it's best cooked within a few days of purchase.