Odonus niger

A fish belonging to the family Balistidae, an animal coming from the Indian and Pacific Oceans: the Red Sea, the Persian Gulf, the Gulf of Aden, Madagascar, the Seychelles, Mauritius, the Maldives, the Australian Great Barrier Reef, Bali, the Philippines, the Solomon Islands, New Guinea, New Caledonia, Samoa, the Hawaiian Islands and Polynesia.

It has a laterally compressed body, an upturned mouth with protruding red or purple teeth, undulating dorsal and anal fins, and a crescent-shaped tail with long, protruding extensions on each side. On the belly and back there are also protruding spines that, used as hooks, form an effective defence system: when chased by predators it can wedge itself inside the stony corals, locking its dorsal and ventral spines, and by staying firmly anchored it prevents itself from being pulled out. The livery is a uniform colour, very dark blue, dark purple or dark green, strongly tending to black; two dark turquoise stripes run from the eye to the mouth; the edges of the dorsal, anal and caudal fins are pale turquoise or light blue.

A hardy and relatively peaceful fish, it is suitable for living with almost all reef fish, even other triggerfish; in very large aquariums, over 500 litres, it also lives with others of its kind; not suitable for aquariums with invertebrates, as it could feed on them.

To keep it in a tank, excellent water quality is needed; in optimal conditions it is an animal resistant to disease; it suffers from low pH and excessive concentrations of nitrate and phosphate; it loves a strong flow.

Once introduced, during acclimatisation, it accepts food with difficulty, but once settled in it is omnivorous; in fact it can be given frozen food, Artemia, chironomus, mysis, mussel flesh, shrimp or small fish. It also likes dry foods and sheets of Nori seaweed and does not refuse vegetables such as lettuce or boiled spinach.

Species sheet by Massimo Ramognino and photo by Flavio Dal Grande