Flounder, sole, halibut, sanddab
Some key flatfish identification characteristics to look for are:
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.
A series of modified scales with pore-like openings to a sensory canal along the side of a fish.
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).
Find more information on individual species of flatfish see: http://wdfw.wa.gov/fishing/bottomfish/identification/flatfish