Species Description: Eucinostomus lefroyi is a member of the family Gerreidae. The Eucinostomus genus is distinguished from other members of the family Gerreidae by the interhaemal cone, an unusual cone-shaped structure formed from the first two anal pterygiophores that encloses the posterior end of the air bladder (Matheson et al. 1984). In general, mojarras are small- to medium-sized silvery compressed fishes.
Potentially Misidentified Species: E. lefroyi is distinguished from other mojarras by the mottled coloration on its back that appears as six wavy lateral lines connected by eight lateral dots. Their body shape ranges from slightly elongate to elongate. The head features a pointed snout and a highly protrusible mouth (Randall 1996). There is a single dorsal fin usually with spines and 10 soft rays. The anal fin has two spines. The dorsal and anal fins fold into a scaly sheath at the base. The caudal fin is deeply forked and covered with small scales.
Regional Occurrence: Members in the family Gerreidae are usually found in muddy and sandy bottoms of estuaries, but are also recorded from fresh water tributaries, sand beaches, shallow reef formations and open waters between the low tide mark and 200 m (Kerschner et. al. 1985, Randall 1996, Chen et al. 2007). Eucinostomus lefroyi occurs in the western Atlantic from North Carolina to Bermuda to the northern Gulf of Mexico to Brazil (Randall 1996). This fish is a major component of estuarine fish communities (Kerschner et. al. 1985). Adults prefer the sandy shores while the distribution of juveniles is more widespread.
IRL Distribution: The mottled mojarra is common in the near shore waters of Florida and occurs mainly in and near inlets of the IRL (Kerschner et al. 1985).
Age, Size, Lifespan: Individual mottled mojarra in the Indian River Lagoon range in size from 10 to 69 mm (Kerschner et al. 1985). The standard length is recorded from the tip of the upper jar to the base of tail and is reported to be 79 to 91 mm. Maximum recorded length is 20.3 cm but adults are usually smaller (Randall 1996).
Abundance: In the Indian River Lagoon, mottled mojarra were recorded to comprise of 10% of the catch of members of the Gerreidae (Kerschner et al. 1985).
Reproduction: Members of the family Gerreidae spawn during the warmer summer months (Godefroid et al. 2001).
Embryology: Larval fishes and juveniles in the family Gerreidae inhabit the shallow estuaries in the warmer summer months (Godefroid et al. 2001).
Trophic Mode: Eucinostomus lefroyi is a benthic feeder and uses its highly protrusible mouth to forage for infaunal invertebrates, feeding primarily on bivalves, copepods, other crustaceans and polychaetes (worms) (Kerschner et al. 1985).
Chen W-J, Ruiz-Carus R, and G Ort'. 2007. Relationships among four genera of mojarras (Teleostei: Perciformes: Gerridae) from the western Atlantic and their tentative placement among percomorph fishes. Journal of Fish Biology 70B:202-218. Delgado P. 2004. Fish, Crustaceans, and Mollusks found in U.S. Caribbean Wetlands, NOAA.
Fishbase. Available online.
Godefroid RS, Santos C, Hofstaetter M, and HL Spach. 2001. Occurrence of larvae and juveniles of Eucinostomus argeneus, Eucinostomus gula, Menticirrhus americanus, Menticirrhus littoralis, Umbrina coroides and Micropogonias furnieri at Pontal do Sul beach, Parana. Brazilian Archives of Biology and Technology 44:411-418.
ITIS. Integrated Taxonomic Information System. Available online.
Kerschner BA, Peterson MS, and RG Gilmore, Jr. 1985. Ecotopic and ontogenetic trophic variation in mojarras (Pisces: Gerreidae). Estuaries 8:311-322.
Matheson, RE, Jr. and JD McEachran. 1984. Taxonomic studies of the Eucinostomus argenteus complex (Pisces: Gerreidae): preliminary studies of external morphology. Copeia 4:893-902.
Randall, JE. 1996. Caribbean Reef Fishes, TFH Publications, Neptune City, NJ ZipCodeZoo. Available online.