Plagioscion is a genus of hardheads, ray-finned fish in the family Sciaenidae. They are found in tropical and subtropical South America where they inhabit fresh and brackish waters. Some species (notably P. squamosissimus and P. surinamensis) are important food fish and support major fisheries.
Depending on the exact species, they reach up to about 30–80 cm (1.0–2.6 ft) in length. In general, the various species are similar and are not easily separated by meristics or colour.
Plagioscion sometimes occur in schools. They are predators and the adults are essentially piscivorous. The largest in the genus, P. squamosissimus, mainly feeds on fish smaller than 15 cm (6 in), but may take ones up to about 60% of the length of the Plagioscion itself.