The sablefish is a species of deep sea fish common to the North Pacific ocean. Adult sablefish are opportunistic feeders, preying on fish (including Alaskan pollock, eulachon, capelin, herring, sandlance, and Pacific cod), squid, euphausiids, and jellyfish.he sablefish is found in muddy sea beds in the North Pacific at depths of 300 to 2,700 m (980 to 8,860 ft) and is commercially important to Japan.