Threadfin Bass

Threadfin Bass, Pronotogrammus multifasciatus

The Threadfin Bass, Pronotogrammus multifasciatus, whose common Spanish name is serrano baga, is a species in the Sea Bass or Serranidae Family, known collectively as serranos in Mexico. Globally, there are three species in the genus Pronotogrammus, all of which are found in Mexican waters, one in the Atlantic and one in the Pacific.  Its common name is derived from its long pelvic fins which are significantly longer than those found in most fish. The Threadfin Bass is an Anthias, a subfamily of Serranidae, that makes up the majority of the pink, orange, red, and yellow reef fish seen swarming in most coral reef photography and film.

The Threadfin Basses are one of the few bright red fish and are found only in very deep waters. They have elongated bodies with short heads. Their eyes are moderate in size, their mouth is oblique, and their lower jaw is projecting. They are characterized by a uniform overall red-pink coloration, very long pelvic fins, short pectoral fins that do not reach the anal fin origin, a forked caudal fin, approximately twenty thin irregular yellow bars along their sides, and a yellow stripe under their eyes. All their fins are red with yellow tips.

The Threadfin Basses aggregate over rocky structures at depths between 240 and 1,000 feet. They reach a maximum of 29 cm (11 inches) in length, as documented by a fish that I caught, and less than 450 grams (1 pound) in weight. They are a small and somewhat rare deep water species and very little is known about their behavioral patterns.

In Mexican waters the Threadfin Bass are found in all waters of the Pacific.

The Threadfin Bass is very easy to identify and cannot be confused with any other species.

The Threadfin Basses are a common catch in the greater Los Cabos area, however when released, they will not return to the deep and are almost immediately consumed by the Magnificent Frigate Bird, Fregata magnificus, who post consumption, will always return to the ocean for drinks of water, providing for splendid entertainment.

Threadfin Bass, Pronotogrammus multifasciatus. Fish caught from coastal waters off Loreto, Baja California Sur, April 2015. Length: 20 cm (7.9 inches). Photo courtesy of Chris Wheaton, Loreto.

Threadfin Bass, Pronotogrammus multifasciatus. Fish caught from coastal waters off La Bocana, Baja California Sur, April 2016. Length: 28.7 cm (11.3 inches). Note the extended anal, caudal and pectoral fin ray extensions for which the fish is named, atypical.