Dragonfish

Dragonfish is a common name for members of the family Stomiidae, a group of predatory mesopelagic and bathypelagic fish found throughout the world's deep oceans. Stomias boa, the boa dragonfish, is a representative species with the elongated, scaleless black body and long chin barbel typical of the group. Dragonfish are equipped with an array of striking adaptations for life in permanent darkness, including light-producing photophores, needle-sharp teeth, and in some species the ability to produce red bioluminescence, a rare trait that allows them to detect prey invisible to most other deep-sea animals. Dragonfish are important mid-level predators in deep-sea food webs and remain among the more elusive and rarely observed fish groups due to their extreme depth range.

Dragonfish have a long, slender, snake-like body adapted for slow-cruising predation in open water.

• Elongated, scaleless body, typically black or dark brown
• Long, luminous barbel hanging from the chin, used as a lure
• Large mouth with numerous long, needle-like, backward-curving teeth
• Rows of small photophores along the sides and belly
• Small eyes relative to head size in many species, though some have well-developed eyes

Dragonfish are distinguished from viperfish by their chin-mounted barbel lure rather than a dorsal fin lure, and from hatchetfish by their elongated, snake-like rather than laterally compressed, disc-shaped body.

Dragonfish inhabit the mesopelagic and bathypelagic zones of oceans worldwide, generally found at depths between about 200 and 2,000 meters, with some species ranging deeper. Like many deep-sea predators, dragonfish undertake vertical migrations, moving toward shallower, food-richer waters at night and retreating to darker, colder depths during the day. They live entirely within the open water column and show no association with the seafloor. Dragonfish favor the permanently dark environment below the reach of sunlight, where their bioluminescent adaptations, including some species' rare red-light photophores, provide a significant advantage for locating prey that cannot detect red wavelengths.

Dragonfish are solitary ambush predators that dangle a luminous chin barbel to attract small fish and crustaceans within striking range of their large, tooth-filled jaws, which can open wide enough to swallow prey close to their own size. Some species produce red bioluminescence from specialized photophores near the eyes, an unusual adaptation that lets them illuminate and detect prey largely invisible to other deep-sea animals, which typically cannot perceive red light. Dragonfish participate in nightly vertical migrations, following prey toward shallower water after dark. Little is known about their reproduction, though like most deep-sea fish they are thought to release pelagic eggs that develop while drifting in open water.