How to Identify Southern Flounder

To identify Southern Flounder (Paralichthys lethostigma), look at these key features.

Physical Characteristics

Body shape

flat

Coloration

Dorsal (eyed) side is typically olive-brown to dark brown, often mottled with darker spots and blotches, allowing for excellent camouflage against various substrates. The ventral (blind) side is white. They possess remarkable chromatophores, enabling rapid color changes to match their surroundings.

Scale type

ctenoid

Mouth position

terminal

Distinctive features

Eyes are typically on the left side of the head (levo-ocular)., Large mouth with prominent, sharp teeth., Absence of ocelli (eye-like spots) on the body, which distinguishes it from some other flounder species., Lateral line is strongly arched over the pectoral fin.

Dorsal fin

Long, continuous dorsal fin originating above the eye, extending almost to the caudal fin. Contains 89-99 soft rays.

Tail fin

Rounded caudal fin (tail fin).

Pectoral fin

Well-developed pectoral fins, with the one on the eyed side being larger.

Distinctive fins

Anal fin is also long and continuous, mirroring the dorsal fin, with 70-78 soft rays. Pelvic fins are small and thoracic.

Identification Tips

1. 1

   Eye Placement

   Southern Flounder are typically 'left-eyed' (levo-ocular), meaning both eyes are on the left side of the head when viewed from the front. This is a key differentiator from right-eyed flounders like Gulf Flounder (Paralichthys albigutta) and Summer Flounder (Paralichthys dentatus), though some individuals can be reversed (dextral).

2. 2

   Body Markings

   Unlike the Gulf Flounder and Summer Flounder, the Southern Flounder generally lacks distinct ocelli (eye-like spots) or prominent dark spots on its body. Its coloration is more uniformly mottled brown or olive, allowing for excellent camouflage.

3. 3

   Mouth Size and Teeth

   Possesses a relatively large mouth with numerous sharp, conical teeth, indicative of its predatory nature.

4. 4

   Lateral Line

   The lateral line is distinctly arched above the pectoral fin on the eyed side.

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