This flatfish identification guide is intended to provide information and key characteristics for the most common flatfish species in Washington marine waters. To access species information, click on a species name below. For each species, information is available on expected sizes, typical distribution, and published ages.
Some key identification characteristics to look for are:
- Anal spine: This is a hard, sharp spine pointing forward and located in front of the anal fin, near the anus.
- Accessory dorsal branch (ADB): A branch of the lateral line running from near the head back toward the tail, just below the base of the dorsal fin.
- Lateral line: A series of modified scales with pore-like openings to a sensory canal along the side of a fish.
- Eyed side: The top side of a flatfish. This side has eyes and is more darkly pigmented than the side that lies against the bottom (blind side).
For additional identification assistance, a dichotomous key for flatfish is available through the Oregon Department of Fish and Wildlife’s website.
The NOAA-Alaska Fisheries Science Center also provides identification information about flatfish common off the Alaskan Coast.