Bigmouth Sanddab, Citharichthys gilberti
Bigmouth Sanddab, Citharichthys gilberti. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, April 2010. Length: 7.5 cm (3.0 inches). Identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, California.
Bigmouth Sanddab, Citharichthys gilberti. Fish caught off the beach with a cast net at the mouth of the San Jose River, Baja California Sur, April 2018. Length: 20 cm (7.9 inches).
The Bigmouth Sanddab, Citharichthys gilberti, is a member of the Sand Flounder or Paralichthyidae Family, and is known in Mexico as lenguado tapadera. Globally, there are twenty-four members of the genus Citharichthys, of which sixteen are found in Mexican waters, eight in the Atlantic and eight in the Pacific Ocean.
The Bigmouth Sanddab has an elongated oval bodies with a depth that is 41% to 45% of standard length. Their eye side is brown with darker brown mottling and scattered white flecks and blotches. Their anal and dorsal fins have dark spots. Their blind slide is off-white to tan. They fade quickly to a uniform brown color upon collection. Their head is relatively short with a medium-sized mouth that ends under the center of their lower eye. Their mid-sized eyes are found on the left side and are separated with the lower eye preceding the upper eye. They have one series of immovable teeth on each jaw and lack canines. Their anal fin has 57 to 65 anal rays; their caudal fin is slightly rounded; their dorsal fin has 76 to 89 dorsal rays; and, their eye side pectoral fin is approximately 50% of the head length. They have 13 or 14 long slender gill rakers on their lower arch. They are covered with rough scales on both sides of their body. Their lateral line is straight and extends from the gill covers to the caudal fin base.
The Bigmouth Sanddab is a demersal species that is found over sandy and muddy bottoms in bays, estuaries, and fresh water at depths up to 37 m (120 feet). They reach a maximum of 30 cm (12 inches) in length and 225 grams (0.5 lb) in weight. They consume a wide variety of crustaceans and small fish and are preyed upon by various marine mammals, larger fish, and sea birds. They are masters at camouflage and can rapidly change colors to match their substrate. They have lifespans of up to ten years. The Bigmouth Sanddab 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 Bigmouth Sanddab is a resident of all Mexican waters of the Pacific Ocean with the exception that they are absent from Guerrero Negro, Baja California Sur, northward along the central and northwest coasts of Baja and for the northern 20% of the Sea of Cortez.
The Bigmouth Sanddab can be easily confused with the Beach Flounder, Syacium latifrons (7 or 8 lower gill rakers), the Five-Rayed Sanddab, Citharichthys mariajorisae (15-17 lower gill rakers), the Gulf Sanddab, Citharichthys fragilis (narrow body, 4-10 lower gill rakers), and the Pacific Sanddab, Citharichthys sordidus (narrower body).
From a conservation perspective the Bigmouth Sanddab is currently considered to be of Least Concern with stable, widely distributed populations. They are a minor component of the commercial fishery with the majority of fish taken as a by-catch of deep water trawls. Although small in stature and rare, they are considered an excellent food fish.