Fish Identification Photos: Gulf Weakfish, Cynoscion othonopterum: The Gulf Weakfish has an overall silver-grey appearance with yellowish fins and is characterized by its oblique mouth that ends before the end of the eye, a projecting lower jaw, a body covered with rough scales, and especially, a concave caudal fin that makes the species fairly easy to identify.

Gulf Weakfish is only found within the confines of the Sea of Cortez, being absent from all other Mexican waters. The Gulf Weakfish is generally found in the first 100 feet of the water column and is reported to reach just over two feet in length. It is viewed by locals as excellent table fare.

The Gulf Weakfish is a member of the Sciaenidae family which includes croakers, corvina, stardrums and weakfish. The weakfish are members of the genus Cynoscion and are characterized by having elongated large oblique mouths and no barbells on their chins.

They have a long dorsal base that is deeply notched and slender spines. The anal fin has two small spines. Globally there are 24 members of this genus of which 8 are found in Mexican waters. They are generally found as bottom dwellers over sandy or muddy bottoms and are sold extensively for food. They are carnivorous, feeding on small fishes and benthic invertebrates.

The Gulf Weakfish is easily confused with the White Weakfish or White Seabass, Atractoscion nobilis (ridge along its belly; inner base of pectoral fins with a black blotch). The Gulf Weakfish is also quite similar in appearance to a series of other corvinas and weakfish, including the Orangemouth Weakfish, Cynoscion xanthulum, the Shortfin Weakfish, Cynoscion parvipinnis, the Totoaba, Totoaba macdonaldi, the Yellowmouth Weakfish, Cynoscion squamipinnis and the Yellowtail Weakfish, Cynoscion stolzmanni, but each of these fish have straight or pointed caudal fins.

Gulf Weakfish, Cynoscion othonopterum: Caught at San Jose del Cabo, Baja California Sur, Mexico, at at Chileno Bay on cut squid about 75 to 100 feet deep, by Tom Klos off Chileno Bay. Photo courtesy Ed Kammer. Fish identification courtesy John Snow.