The black durgon or Melichthys niger is a fish of the family Balistidae belonging to the order Tetraodontiformes. It inhabits the shallow waters (less than 30 meters deep) of the outer reefs on both sides of the tropical Atlantic Ocean. In the eastern Atlantic Ocean it is distributed from the coasts of the Gulf of Guinea, Ascension and St. Helena Islands. In the western Atlantic Ocean, from south Florida to Brazil, including the Bahamas, Bermuda and the Caribbean Sea, although absent in the waters of the Gulf of Mexico. Melichthys niger is also present in Indo-Pacific waters.
The body of Melichthys niger is usually about 30 cm long, with specimens up to 50 cm long. It adopts an oval shape, laterally compressed. They have a terminal mouth of small size and equipped with teeth whose edges are uniform between them and straight. In juvenile specimens, if there may be notches between the teeth, this is because the teeth have not yet been worn down enough to make them disappear. A little above the mouth and towards the eyes, there is a small indentation. The eyes are small in size and are located above the midline of the body and positioned laterally. It has two dorsal fins, a first one formed by 3 spines, of which the first one is very robust and the third one very small. The second region is formed by 32-34 soft rays and run in the posterior third of the body to the caudal peduncle. The anal fin, with 28-31 soft rays, is located in the same vertical as the second dorsal fin. The caudal fin has the upper and lower rays slightly longer than the central ones. The body color of Melichthys niger is black with greenish tones. The outline of the scales has an ephemeral orange-red hue, especially in the head area where it forms a diamond pattern. It has pale blue or whitish bands along the bases of the second dorsal and anal fins.
The diet of Melichthys niger is based on a multitude of algae and planktonic invertebrates.
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