Tidewater Mojarra, Eucinostomus harengulus
Tidewater Mojarra, Eucinostomus harengulus. Fish caught from coastal brackish waters of Plantation, Florida, March 2017. Length: 5.4 cm (2.0 inches). Catch, photograph, and identification courtesy of Ryan Crutchfield, Tampa, Florida.
Tidewater Mojarra, Eucinostomus harengulus. Fish caught from coastal waters off Cudjoe Key, Florida, March 2017. Length: 15.2 cm (6.0 inches). Catch, photograph, and identification courtesy of Kenneth Tse, Toronto, Ontario, Canada.
Tidewater Mojarra, Eucinostomus harengulus. Fish caught from coastal waters off Titusville, Florida, August 2019. Length: 15.2 cm (6.0 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Note: This is a difficult fish to correctly identify. The above identifications should be considered 90% certain. A correct identification is only possible by an examination of the interhaemal cone that is uniquely shaped being formed from the first two anal pterygiophores that enclose the posterior end of the air bladder. This was not done with this specimen as it was returned to the ocean unharmed. The best alternative is the Spotfin Mojarra, Eucinostomus argenteus.
The Tidewater Mojarra, Eucinostomus harengulus, is a member of the Mojarra or Gerreidae Family, and is known in Mexico as mojarra cubana. Globally, there are eleven species in the genus Eucinostomus, and all eleven are found in Mexican waters, seven in the Atlantic and four in the Pacific Ocean.
The Tidewater Mojarra has a compressed, fusiform, oval body with a depth that is 33% to 37% of standard length. They are silvery in color with six dark blotches along the mid-side that join seven oblique bars on the upper back; they have a broad black area at the margin of the front portion of the first dorsal fin. Their head has a very concave lower profile, with a pointed snout and a highly extensible, downward pointing mouth when extended that is equipped with minute brush-like teeth. The anal fin has 3 weak spines, the second of which is short, and 8 rays; their caudal fin is deeply forked; their first dorsal fin has 9 spines; their second dorsal fin has 10 rays; and, their pectorals are short and do not reach the anal fin origin. They have 7 or 8 lower gill rakers. The body is covered with large rough scales.
The Tidewater Mojarra is a schooling species that is found in estuaries over sandy vegetated substrate and also over mud bottoms around mangroves and open sandy beaches at depths up to 10 m (33 feet). They can be found in both brackish and freshwater environments. They reach a maximum of 15 cm (5.9 inches) in length. They feed primarily on benthic invertebrates including crustaceans, mollusks, and polychaetes. They utilize freshwater environments to avoid predation by salt water predators. Reproduction is oviparous. The Tidewater Mojarra 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 Tidewater Mojarra is a resident of Mexican waters and has a limited distribution, being found in the coastal waters from the Texas border south to Laguna Madre, Tamaulipas, and from Campeche, eastward to the tip of the Yucatán Peninsula in the Gulf of Mexico and along the East Coast south to Belize in the Caribbean.
The Tidewater Mojarra is very similar to a series of other small silvery Mojarras found in Mexican waters of the Caribbean including the Mottled Mojarra, Eucinostomus lefroyi, the Slender Mojarra, Eucinostomus jonesii, the Silver Jenny, Eucinostomus gula, and the Spotfin Mojarra, Eucinostomus argenteus, but all lack the dark tip on the dorsal fin margin found in the Tidewater Mojarra.
From a conservation perspective the Tidewater Mojarra is currently considered to be of Least Concern with stable, widely distributed populations. They are small in stature and are of limited interest to most. In some areas they are caught with cast nets, beach seines, handlines, set nets, and bottom trawls. They are utilized as a live bait for Tarpon in some areas. Their long-term viability is threatened by human development including agricultural runoff, habitat destruction, pesticides, and sewage.
NOTE. There are eighteen members of the Mojarra or Gerreidae Family currently Included in this website, ten are from Mexican waters of the Pacific and eight from the Atlantic. They are all very similar in appearance and difficult to identify. As an aide to this challenge I have assembled a Mojarra Body Depth Chart that presents these seventeen mojarras from thin bodied to deep bodied which is useful in identification work. In addition, I have also assembled a Mojarra Maximum Length Chart which I have also helpful in the identification work for these eighteen mojarras. Both charts can be found at the end of the Mojarra Family Page.