Ramnogaster melanostoma

Common Name

Uruguay River Sprat

Year Described

Eigenmann, 1907


Dorsal Fin: 15-16
Anal Fin: 17-20
Pelvic Fin: 6 branched
Pectoral Fin: 12-14
Ventral Scutes:
Gill Rakers: 36-28 (first arch)

Body fusiforme, rather deep (27-41% SL), and compressed. Posterior gill margin rounded with no fleshy lobes. Eye a little smaller than snout length. Upper jaw without median notch and reaching to eye. Supramaxilla (first anterior) minute or absent. No backward pointing spine on maxilla. Dorsal and ventral profiles convex. Dorsal fin origin centered at about midbody and has a concave margin. Pelvic fin under dorsal fin origin. Anal fin low with origin under last dorsal ray. Pectoral fin low on chest. Tail forked. Body scaled. Ventral scutes with strong keels.


Body silvery with a greenish to dusky back. Caudal fin dusky with a dark margin. Rest of fins clear. No silvery stripe.


Maximum size to 10cm SL.


Primarily in freshwater, but also in river mouths and brackish estuaries.


Rio de la Plata and associated rivers in Argentina and Uruguay.


Whitehead, P.J.P. 1985. FAO Species Catalogue. Vol. 7. Clupeoid fishes of the world (suborder Clupeoidei). An annotated and illustrated catalogue of the herrings, sardines, pilchards, sprats, shads, anchovies and wolf-herrings. FAO Fish. Synop. 125(7/1):1-303. Rome: FAO.

Other Notes

Whitehead (1985) notes two ecotypes of this species named as subspecies: Ramnogaster m. melanostoma and R. m. limnoica. The latter is much more deep bodied and occurs in brackish water more frequently.