Spotfin Mojarra

Spotfin Mojarra, Eucinostomus argenteus

The Spotfin Mojarra, Eucinostomus argenteus, whose common Spanish name is mojarra plateada, is a species in the Mojarra or Gerreidae Family, known collectively as mojarras in Mexico. Globally, there are eleven species in the genus Eucinostomus, all of which are found in Mexican waters, seven in the Atlantic and four in the Pacific.

The Spotfin Mojarras have elongated oval bodies with a depth that is 32 to 36% of standard length. They are silvery in color with some fish having a unique and very subtle mottling pattern of seven bars separated by six dark lateral spots on their sides. The tip of their dorsal fin is dusky. Their snout has a distinctive V-shaped pigmentation. Their head has a pointed snout, a concave lower profile, and a highly extensible mouth that points downward. Their anal fin has 3 spines and 8 rays; their caudal fin is deeply forked; and their dorsal fin has 9 spines and 10 rays. Their body is covered with large rough scales.

The Spotfin Mojarras is a schooling species that reside in coastal areas over soft bottoms in bays and shallow inshore areas. They are also known to enter freshwater with juveniles found in and around mangroves. They reach a maximum length of 15.0 cm (5.9 inches). They are benthic feeders consuming bivalves, crustaceans, and polychaete worms. They are a poorly studied species and very limited information is available about their behavioral patterns.

In Mexican waters the Spotfin Mojarra are found in all waters of the Atlantic.

The Spotfin Mojarra is most likely confused with the Mottled Mojarra, Eucinostomus lefroyi (different mottling profile), the Silver Jenny, Eucinostomus gula (wider body depth, 38- 42%), the Slender Mojarra, Eucinostomus jonesii (narrower body depth, 30-32%), and the Tidewater Mojarra, Eucinostomus harengulus (different mottling profile).

The Spotfin Mojarras are marketed fresh but are not in high demand. They are also processed into fish meal. They can be used as live bait for snappers.

Spotfin Mojarra, Eucinostomus argenteus. Fish caught from coastal waters off  Sugarloaf Key, Florida, June 2015. Length: 13.8 cm (5.4 inches). Catch and photo courtesy of Dean Kimberly, Atlanta, GA. Note: This fish identification 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.