A new gerreid fish species, Gerres mozambiquensis, is described on the basis of a holotype and one paratype from Larde Estuary, southern Nampura, Mozambique. The species is characterized by the following unique combination of characters: relatively deep body (greatest depth 46–47% SL); robust second anal-fin spine (greatest width of second spine/greatest width of third spine  =  1.7–1.8); three supraneural bones configuration (0/0/0 2/); dorsal fin with nine spines and ten rays; lateral-line scales 43 or 44; 4 or 4½ scales between fifth dorsal-fin spine base and lateral line; caudal-fin lobes short, the tips rounded with growth; and six to eight indistinct dark vertical bars (bar width about half pupil diameter) on lateral surface of body. Gerres maldivensis Regan, 1902, formerly considered a junior synonym of G. erythrourus (Bloch, 1791) ( =  G. abbreviatus), is reinstated as a valid Indo-Pacific species. It is characterized by body depth 43% SL, approximately eight faint dark vertical bars on body, lateral-line scales 40, 5½ scales between fifth dorsal-fin spine base and lateral line, 5½ and 9½ scale rows above and below the lateral line, respectively, dorsal surface of head with two converging rows of minute scales surrounded by series of larger scales, two small scales near the premaxillary groove, but no scales on the groove itself, and three supraneural bones (0/0/0 2). This suite of diagnostic characters is not known for any other species of Gerres. Several nominal species of Gerres of uncertain status are also discussed.