Intermediate Flounder

Intermediate Flounder, Etropus ciadi

The Intermediate Flounder, Etropus ciadi, whose common Spanish name is lenguado intermedio, is a member of the Sand Flounder or Paralichthyidae Family, known collectively as lenguados areneros in Mexico. This fish is also known as the Cortez Flounder. Globally there are nine members of the genus Etropus, five of which are found in Mexican waters, two in the Atlantic, two in the Pacific, and one in both the Atlantic and the Pacific.

The Intermediate Flounders are left-eyed flat fish with a complete and relatively straight lateral line that starts at the top corner of their gill cover. They have elongated oval deep bodies with a depth that is 51 to 55% of standard length. Their eye side is brown with dark brown speckles and spots on the body, anal fins, and dorsal fins. Their pectoral fins have a dark tip and a wavy bar. Their blind side is off-white to tan. They have a short pointed head with a relatively large mouth for this genus, which ends just before the front edge of their lower eye. Their eyes are set very close together with the lower eye slightly in front of the top eye. They have one row of teeth on both jaws. They have 52 to 62 anal rays and 66 to 79 dorsal rays. Their caudal fin has a rounded point. They have two to 7 gill rakers on their lower arch and are covered with small rough scales.

The Intermediate Flounders are bottom dwellers found over and within sandy and muddy bottoms at depths up to 140 feet. They reach a maximum length of 11.6 cm (4.6 inches). They are opportunistic and well-camouflaged ambush predators that lie in wait half submerged on the ocean floor.

In Mexican waters the Intermediate Flounder have a very limited range being found only along the east coast of the Sea of Cortez.

The Intermediate Flounder can possibly be confused with the Fringed Flounder, Etropus crossotus (small mouth) and the Peruvian Flounder, Etropus peruvianus (body depth less than 50% of standard length).

The Intermediate Flounder is too small and too rare to be of interest to most.

Intermediate Founder, Etropus ciadi. Fish provided by the commercial fishermen of Bahía Kino, Sonora, January 2015. Length: 10.1 cm (4.0 inches). Photo courtesy of Maria Johnson, Prescott College Kino Bay Center, Kino Bay, Sonora.