Odontesthes bonariensis is a species of Neotropical silverside, an euryhaline fish native to fresh, brackish and salt water in south-central and southeastern South America, but also introduced elsewhere. It is often known by the common name Argentinian silverside or pejerrey (the latter is of Spanish origin), but it is not the only species of silverside in Argentina and pejerrey is also used for many other silversides. It is a commercially important species and the target of major fisheries.