Threadfin Bass

Threadfin Bass, Pronotogrammus multifasciatus

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

Threadfin Bass, Pronotogrammus multifasciatus. Fish caught from coastal waters off Loreto, Baja California Sur, January 2019. Length: 21 cm (8.3 inches). Catch, photograph and identification courtesy of Chris Wheaton, Fullerton, California.

Threadfin Bass, Pronotogrammus multifasciatus. Fish caught from coastal waters off Los Barriles, Baja California Sur, December 2020. Length: 28 cm (11 inches). Catch, photograph and identification courtesy of Chip Shapley, Los Barriles. Note the extended anal, caudal and pectoral fin ray extensions for which the fish is named, atypical.

Threadfin Bass, Pronotogrammus multifasciatus. Fish caught from coastal waters off Los Barriles, Baja California Sur, May 2020. Catch and photograph courtesy of Chip Shapley, Los Barriles.

The Threadfin Bass, Pronotogrammus multifasciatus, is a member of the Sea Bass or Serranidae Family, and is known in Mexico as serrano baga. Globally, there are three species in the genus Pronotogrammus, all of which are found in Mexican waters, one in the Atlantic and two in the Pacific Ocean. Its common name is derived from its long pelvic fins which are significantly longer than those found in most fish. The Threadfin Bass is a member of the Anthias Family, 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 Bass is one of the few bright red fish and are found only in very deep waters. Their body is elongated bodies with a short heads that has moderately sized eyes, an oblique mouth and a projecting lower jaw. They are a uniform overall red-pink color. approximately twenty thin irregular yellow bars along their sides, and a yellow stripe under their eyes. All their fins are red with yellow tips. Their anal fin has 3 spines and 7 or 8 rays; their caudal fin is forked; their dorsal fin has 10 or 11 spines and 14 or 15 rays; their pectoral fins have 18 to 20 rays and reach the anal fin origin; and, their pelvic fins have a very long second ray that reaches past the anal fin spines. They have 37 to 42 gill rakers. They are covered with scales.

The Threadfin Bass aggregate over rocky structures at depths between 73 m (240 feet) and 305 m (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 lb 0 oz) in weight. The Threadfin Bass is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Threadfin Bass is a resident of all Mexican waters of the Pacific Ocean.

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

From a conservation perspective the Threadfin Bass is currently considered to be of Least Concern with stable, widely distributed populations. They are a common catch in the greater Los Cabos area of Baja California Sur, and retained only by subsistence fishermen. Efforts at “catch and release” normally do not go well as they will not return to the deep and float on the surface and are almost immediately consumed by the ever vigilant Magnificent Frigate Bird, Fregata magnificus, who post consumption, will always return to the ocean for drinks of water, providing for splendid entertainment.