mojarra, any of approximately 40 species of fishes in the family Gerreidae (order Perciformes), found in marine environments in most warm regions of the world. Brackish habitats or fresh water are entered on occasion by some species. Mojarras are silvery fishes with compressed bodies; they are distinguished by their highly protrusible mouths, with the opened jaws forming an extended tube. Although their maximum length is about 35 cm (14 inches), most species of mojarra do not attain lengths greater than 25 cm (10 inches). The spotfin mojarra (Eucinostomus argenteus), which is one of the most widespread species, occurs along the Atlantic, Gulf of Mexico, and Pacific coasts of North America, even entering freshwater habitats in the lower reaches of river systems.