Buy Your License Online! Buy Your License Online!

Bottomfish Identification: Flatfish

Butter Sole
Pleuronectes isolepis

Occasionally caught off the Washington coast by commercial harvesters using otter-trawls.  Occasionally caught by recreational harvesters in the South and Central Puget Sound regions. 

Description: This sole is right-eyed with an oval body shape. The eyed side is rough-scaled and light to dark brown, or grayish brown with yellow or green mottling.  The scales extend onto the fin rays.  The blind side is white.  The upper eye is not visible from the blind side.  The dorsal and anal fin edges are typically bright yellow. The caudal fin is rounded to a broad V shape. The lateral line has a low arch over the pectoral fin and a long accessory dorsal branch that extends past the gill cover. Butter sole have a small mouth with blunt teeth; the strongest teeth are on the blind side. The maxillary extends just below the anterior part of the upper eye. Between the eyes is a flat narrow space and the eyes are small. This species has a strong anal spine. Butter sole are easily confused with rock sole, which have a higher arch in the lateral line and a shorter accessory dorsal branch.

Maximum Size: To 55 cm (22 in) in length, with an average length of about 20.3 cm (8 in).

Maximum Age: 11 years old.

Range/Habitat: Butter sole range from the southern Bering Sea and Aleutian Islands south to Ventura, southern California. They are typically found on muddy or silty bottoms from 0 to 425 m (0-1,395 ft) in depth. Butter sole are common in shallow water, and are most abundant shallower than 91 m (300 ft).


  • Kramer, D. E., & Josey, T. (1995). Guide to Northeast Pacific flatfishes: families Bothidae, Cynoglossidae and Pleuronectidae. Sea Grant.

Photos: S. Axtell