Southern Flounder Identification Guide
Identify southern flounder by its left-eyed body, large mouth, and plain, spot-free brownish-olive coloring.
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Key identification features
- Left-eyed flatfish with a large, elongated oval body
- Large mouth lined with sharp teeth, extending well back beneath the eye
- Uniform brownish-grey to olive mottled upper side, generally lacking distinct ocellated spots
- Pale, unmarked underside
- Moderately arched lateral line above the pectoral fin
- Can grow quite large for a flounder, often exceeding 50 cm
Common look-alikes
- Summer flounder – overlaps in range in the mid-Atlantic but shows faint, loosely arranged eyespots that southern flounder lacks.
- Gulf flounder – displays three bold, well-defined dark spots forming a triangle pattern on the back, unlike southern flounder's plain coloring.
- Southern founder juveniles vs. other left-eyed flounders – best separated by the near total absence of spotting at any size.
Where you'll see one
Southern flounder are found in estuaries, bays, and coastal waters of the western Atlantic and Gulf of Mexico, ranging roughly from North Carolina south through Texas. They tolerate a wide range of salinities and often move well into brackish or low-salinity estuarine habitat.
Frequently asked questions
How do I tell southern flounder apart from Gulf flounder in the same waters?
Look for spots: Gulf flounder shows three bold dark spots arranged in a triangle, while southern flounder's back is largely plain and unmarked.
Can southern flounder be confused with summer flounder?
Yes, where their ranges overlap, but summer flounder typically shows faint ocellated spots that southern flounder generally lacks, helping tell the two apart.