Black Durgon, Melichthys niger

Black Durgon, Melichthys niger. Fish caught from within Kealakekua Bay, Captain Cook, Hawaii, March 2019. Length: 17 cm (6.7 inches). Catch, photograph and identification courtesy of Marc Eberlein, Grand Rapids, Michigan.

Black Durgon, Melichthys niger. Fish caught from coastal waters off Kona, Hawaii, July 2014. Length: 24 cm (9.4 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

Black Durgon, Melichthys niger. Underwater photograph taken in coastal waters off Kailua-Kona, Hawaii, February 2015. Photograph courtesy of Bob Hillis, Ivins, Utah.

Black Durgon, Melichthys niger. Underwater photograph taken in coastal water around Isla Ixtapa, Guerrero, March 2018. Photograph courtesy of Ron Woheau, Zihuantanejo.

The Black Durgon, Melichthys niger, whose common Spanish name is cochito negro, is a member of the Triggerfish or Balistidae Family, that is also known as the Black Triggerfish, Black-finned Triggerfish and the Indian Triggerfish and in Mexico as cochito negro. Globally, there are three species in the genus Melichthys, of which one is found in Mexican waters of both the Atlantic and the Pacific Oceans.

The Black Durgon has an elongated, oval, robust, and compressed body with a depth that is 40% to 43% of standard length. They are very colorful having a pale blue base color covered with black diamond spots forming inconsistent dark lines throughout their body. They have black wavy lines radiating dorsally and anteriorly from their eyes. They have a pale blue-white line along the base of their anal and dorsal fins. All their fins are black. Their head has a wide yellow bar than runs from the beak to the center of the eyes. They are capable of changing colors to match their surroundings. They have small eyes and a small mouth that opens just above the center line and is equipped with heavy outer teeth on the upper and lower jaws. They have a small gill slit on their sides before the pectoral fin base. Their anal fin has 28 to 32 rays with the anterior rays being elevated; their caudal fin is strongly concave; their first dorsal fin has 3 spines, and can be locked erect; their second dorsal fin has 30 to 35 rays and is about half the length of the first with the anterior rays being elevated; their are 8 to 10 lateral ridges on the rear of their body and caudal base; and, their pelvic fins are minute. They are covered with thick scales. Their lateral line is inconspicuous.

The Black Durgon is a benthopelagic species found on the slopes of oceanic reefs and around oceanic islands at depths up to 75 m (250 feet). They are found in small loose aggregations of up to 200 individuals. They reach a maximum of 51 cm (20 inches) in length. As of January 1, 2024, the International Game Fish Association world record stood at 0.91 kg (2 lbs 0 oz) with the fish caught in coastal waters off Cuba in August 2017. They are omnivores that feed on small fish, algae, phytoplankton, shrimp, squid, and zooplankton. Reproduction is oviparous. They have lifespans of six years. The Black Durgon 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 Black Durgon has a very wide global distribution which is attributed to their long pelagic stage. In Mexican waters, they are found in all oceanic waters of the Atlantic and Pacific Oceans but with only limited documented populations in widespread and generally remote areas. In the Gulf of Mexico they are considered uncommon but are found in in coastal waters from Veracruz to the Yucatán Peninsula. In the Pacific, they have been found in numerous widely spaced specific locations and are abundant around the Clipperton Islands.

The Black Durgon is easy to identify within its range and cannot be confused with any other species. However, the Indian or Black-finned Triggerfish, Melichthys indicus from the Indian Ocean can be easily mistaken for a Black Durgon in the aquarium trade.

From a conservation perspective, they are currently considered to be of Least Concern with stable, widely distributed populations. They are sold commercially for human consumption and marketed fresh on a limited basis. They are used extensively by the aquarium trade due to their beauty and ease of care although they can be aggressive.