Diapterus auratus, the Irish mojarra or Irish pompano, is a species of ray-finned fish from the family Gerreidae, the mojarras. Other common names for this species are the broad shad, silver perch and muttonfish. It is found in the warmer waters of the western Atlantic Ocean. Diapterus auratus has a rhomboidal, compressed body with the head showing a lower profile which is distinctively concave. It has a very extensible mouth which points downwards when protruded. The jaws are equipped with tiny, brush-like teeth, although they appear to be toothless, and there are pointed teeth inside the throat. The tail is fin deeply forked. It has large, conspicuous scales which have a rough texture created by a fine serrations on the scales. The scales cover most of the head and body. The dorsal and anal fins fold into an elevated scale-covered sheath which runs along the base of these fins. The colour is silvery to olive overall, slightly darker on the upperside,[3] and the spiny dorsal fin has a thin black edge. The juveniles have three narrow vertical dark bars. The pelvic and anal fins are coloured yellow while the rest of the fins are translucent or dusky. The second spine in the anal fin is longer and thicker than the third spine and the rays. The maximum recorded total length is 34 centimetres (13 in) but a more common total length is 20 centimetres (7.9 in) while the maximum published weight is 680 grams (1.50 lb). Diapterus auratus is found in the western Atlantic Ocean where its distribution extends from the south eastern United States, along the Gulf of Mexico coast from western Florida to the Yucatan, through the Caribbean Sea and along the Central American coast and then along the northern and eastern coasts of South America to São Paulo, Brazil. The juveniles are more widespread than the adults and this species is a vagrant to the Atlantic coast of the United States as far north as New Jersey.
