Blackfin Snook

Blackfin Snook, Centropomus medius

The Blackfin Snook, Centropomus medius, whose common Spanish name is robalo aleta prieta, and known locally as robalo, is a species in the Snook or Centropomidae Family, known collectively as robalos in Mexico. Globally, there are twelve species in the genus Centropomus, and all twelve are found in Mexican waters, six in the Atlantic and six in the Pacific.

The Blackfin Snooks have oblong elongated compressed bodies. They are silvery fish with a prominent dark lateral line. Their anal fin is transparent with a black membrane between the second and third spines; their caudal fin is transparent with a black lower lobe; their dorsal fin is transparent with a black membrane between the second and third spines; their pectoral fins are transparent with a black fin base; and their pelvic fins are transparent. Some fish have pelvic fins with black outer rays. They have a slightly concave shovel-shaped upper head profile, with a large protractile terminal mouth, a protruding lower jaw, and large eyes. Their second anal spine is thicker than the third but equal in length; their third dorsal spine in longer than the fourth; their pectoral fins are shorter than the pelvic fins; and their pelvic fins are inserted behind the pectoral fins.

The Blackfin Snooks are found in bays, estuaries, the lower parts of freshwater streams, and where dry river beds meet the ocean (presumably due to subterranean water flow) at depths up to 80 feet. They reach a maximum length of 56 cm (22 inches) and weigh approximately 3 kg (6.6 pounds).

In Mexican waters the Blackfin Snook have a limited distribution being found from Magdalena Bay southward along the southwest coast of Baja, in the southern half of the Sea of Cortez, and along the coast of the mainland south to Guatemala. They are more abundant in the southern portions of this range.

The Blackfin Snook is most likely confused with the Black Snook, Centropomus nigrescens and the White Snook, Centropomus viridis (third dorsal spines much longer than first and second in both fish).

The Blackfin Snook is small and fairly rare, thus not of significant interest to most.

Blackfin Snook, Centropomus medius. Fish caught from the San José Rio, Baja California Sur, with a cast net during a breach in the barrier, January 2011. Length: 24.5 cm (9.6 inches).