The Chilean sea bass is not really bass? Otherwise known as the Patagonian toothfish, this large, slow-growing species was first harvested by Chilean longliners near the coast of Antarctica. While average market weight is around 20 pounds, some specimens may weigh in at nearly 100 pounds—headed and gutted! Chilean sea bass are typically frozen at sea, so most product is usually indicated as “refreshed” fish that has been frozen and subsequently thawed.