Twospot Flounder, Bothus robinsi

Twospot Flounder, Bothus robinsi. Fish caught from coastal waters off Broward County, Florida, June 2021. Length: 8.2 cm (3.2 inches). Catch, photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.

The Twospot Flounder, Bothus robinsi, is a member of the Lefteye Flounder or Bothidae Family, that is known in Mexico as chueco dos manchas. Globally, there are eighteen species in the genus Bothus, of which six are found in Mexican waters, four in the Atlantic and two in the Pacific Ocean. All family members are left eyed fish with an arched lateral line.

The Twospot Flounder has a deep oval body that is laterally flattened with a depth that is 65% to 76% of standard length with a front profile that has a distinct notch before the lower eye. They vary in color being dark brown and covered with scattered, indistinct tan or brown rosettes with a large dark blotch on the mid-body. Their caudal fin has two central spots, one behind the other, for which they are named. Their eyes are large and located on the left side with lower eye being before the upper with a wide space in between that is wider in males than in females. Their mouths are small and end under the front eye that is equipped with small teeth on both jaws. Their anal fin has 59 to 68 rays; their caudal fin is broadly rounded; their dorsal fin has 78 to 90 rays; their eyed-side pectoral fin as 8 to 11 rays and is elongated in males; and, their blind side pelvic fin originates under the lower eye and has a long base. They have 5 to 9 gill rakers on the lower arch. The lateral line is only present on the eye side and is strongly arched above the pectoral fin. They are covered with scales.

The Twospot Flounder is a demersal species that is typically found half buried in sandy substrate in bays, lagoons and shallow coastal waters. They reach a maximum length of 25 cm (9.8 inches). They are found at depths up to 90 m (300 feet). They are lie-in-wait active daytime ambush predators that feed on crustaceans, polychaetes and mollusks.  In turn they are preyed upon by both invertebrates and vertebrates. Their eggs and larvae are consumed by ctenophores, fish, jellyfish, shrimps and worms as-well-as by birds including egrets, gulls and herons. Juveniles are preyed upon by crabs, fish and shrimp. Adults are preyed upon by a wide variety of fishes including eels, groupers, the recently introduced highly invasive Red Lionfish, Pterois volitrans, rays, skates and sharks as-well-as seals and sea lions.  The Twospot Flounder is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Twospot Flounder is most likely confused with the Eyed Flounder, Bothus ocellatus (lack prominent large spots on the caudal fin), the Mottled Flounder, Bothus maculiferus (blue rings, narrower body with a depth that is 50% to 55% of standard length) and the Peacock Flounder, Bothus lunatus (body covered with blue rings).

In Mexican waters the Twospot Flounder is found in the Atlantic Ocean in all waters of the Gulf of Mexico; they are absent from along the east coast of the Yucatán Peninsula in the Caribbean.

From a conservation perspective the Twospot Flounder is currently considered to be of Least Concern with a stable, widely distributed population. They are small in stature and of limited interest to most with the exception that they are caught primarily by artisanal fishermen and retained for human consumption by subsistence fishermen. They are also a by-catch of shrimp trawlers and sold at a small level in Mexico for human consumption.