Grey Chub

Kyphosus bigibbus, commonly known as the brown chub, grey drummer, or insular rudderfish, is a marine ray-finned fish from the Kyphosidae family. This herbivorous species inhabits subtropical and tropical seas globally.

Morphologically, Kyphosus bigibbus features an oval, laterally compressed body with a small head, pointed snout, and slightly bulging forehead. Its small terminal mouth, which is almost oblique, conceals the maxilla beneath preorbital bones when closed. The fixed, incisiform teeth are J-shaped with rounded crowns, located horizontally in the mouth, including the roof and tongue areas. The dorsal fin is consistently elevated along its length, comprising an anterior section with 11 spines and a posterior section with 10-12 rays. The anal fin includes three spines and 10-12 soft rays, with a moderately long base. The caudal fin is symmetrically forked. The lateral line contains 61-76 scales, of which 51-60 are pored. The species exhibits a color range from uniform grey to brownish, with a silvery ventral side and a bronze to green dorsum. Indistinct dark stripes and whitish streaks on the cheek are commonly observed. The dorsal and anal fins are typically dark with black margins on the soft-rayed parts, while a dark patch may appear near the pectoral fin's base. The caudal fin is generally dark. Occasional yellow and rare albino specimens have been reported. The maximum recorded length is 75 centimeters, with a weight of up to 1.9 kilograms.

The distribution of Kyphosus bigibbus spans the 🇮🇳 Indian, Pacific, and Atlantic Oceans. In the Indo-Pacific region, it is found from Western Australia to northeastern 🇳🇿 New Zealand and various islands, while in the 🌊 Indian Ocean, its range likely extends from 🇲🇲 Myanmar to 🇾🇪 Yemen and includes the waters around 🇲🇬 Madagascar and Réunion. Records from the 🌊 Persian Gulf are absent. In the Western Pacific, it inhabits areas from southern 🇯🇵 Japan to 🇹🇼 Taiwan, excluding equatorial regions. The species has been observed off 🇧🇲 Bermuda and other locations in the Atlantic, including around Saint Helena and Madeira, and potentially along the west African coast to 🇿🇦 South Africa. Although noted in northwestern Africa and Portugal, it has not been detected in the Mediterranean. Additionally, sightings have been documented in 🇧🇷 Brazil.

Kyphosus bigibbus typically resides in shallow coral and rocky reefs, especially around exposed offshore reefs and islands, in depths up to 20 meters. It often coexists in mixed schools with related species, while juveniles use floating debris for long-distance dispersal. Its diet primarily consists of algae from the Sargassum and Turbinaria genera.

Although not widely targeted by fisheries throughout its range, when caught, Kyphosus bigibbus is appreciated as a food source. The species was initially described by Bernard Germain de Lacépède in 1801, with the type locality designated as Fort-Dauphin, 🇲🇬 Madagascar.