The common snook (Centropomus undecimalis) is a species of marine fish in the family Centropomidae of the order Perciformes. The common snook is also known as the sergeant fish or robalo. It was originally assigned to the sciaenid genus Sciaena; Sciaena undecimradiatus and Centropomus undecimradiatus are obsolete synonyms for the species.

One of the largest snooks, Centropomus undecimalis grows to a maximum overall length of 140 centimetres (4.6 ft) but common length is 50 centimetres (1.6 ft).The IGFA world record is 24.32 kg (53 lb 10 oz) caught in Parismina Ranch, Costa Rica by an angler named Rafael Montalvo.^[1][2] Of typical centropomid form, it possesses drab coloration except for a distinctive black lateral line. It can also possess bright yellow pelvic and caudal fins, especially during spawn.^[3]