Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep sea fishes include the flashlight fish, cookiecutter shark, bristlemouths, anglerfish, viperfish, and some species of eelpout.
The Squaliformes are an order of sharks that includes about 126 species in seven families.
Stomiiformes is an order of deep-sea ray-finned fishes of very diverse morphology. It includes, for example, dragonfishes, lightfishes, loosejaws, marine hatchetfishes and viperfishes. The order contains 4 families with more than 50 genera and at least 410 species. As usual for deep-sea fishes, there are few common names for species of the order, but the Stomiiformes as a whole are often called dragonfishes and allies or simply stomiiforms.
The marine hatchetfishes or deep-sea hatchetfishes as well as the related bottlelights, pearlsides and constellationfishes are small deep-sea ray-finned fish of the stomiiform family Sternoptychidae. They are not closely related to and should not be confused with the freshwater hatchetfishes, which are teleosts in the characiform family Gasteropelecidae. The Sternoptychidae have 10 genera and about 70 species altogether.
Fangtooths are beryciform fish of the family Anoplogastridae that live in the deep sea. The name is from the Greek anoplo, meaning "unarmed", and γαστήρ, meaning "stomach". With a worldwide distribution in tropical and cold-temperate waters, the family contains only two very similar species in one genus, with no known close relatives.
Lanternfish are small mesopelagic fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represented by 246 species in 33 genera, and are found in oceans worldwide. Lanternfishes are aptly named after their conspicuous use of bioluminescence. Their sister family, the Neoscopelidae, are much fewer in number but superficially very similar; at least one neoscopelid shares the common name "lanternfish": the large-scaled lantern fish, Neoscopelus macrolepidotus.
Telescopefish are small, deep-sea aulopiform fish comprising the small family Giganturidae. The two known species are within the genus Gigantura. Though rarely captured, they are found in cold, deep tropical to subtropical waters worldwide.
Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs.
A viperfish is any species of marine fish in the genus Chauliodus. Viperfishes are mostly found in the mesopelagic zone and are characterized by long, needle-like teeth and hinged lower jaws. A typical viperfish grows to lengths of 30 cm (12 in). Viperfishes undergo diel vertical migration and are found all around the world in tropical and temperate oceans. Viperfishes are capable of bioluminescence and possess photophores along the ventral side of their body, likely used to camouflage them by blending in with the less than 1% of light that reaches to below 200 meters depth.
Stomiidae is a family of deep-sea ray-finned fish, including the barbeled dragonfishes. They are quite small, usually around 15 cm, up to 26 cm. These fish are apex predators and have enormous jaws filled with fang-like teeth. They are also able to hinge the neurocranium and upper-jaw system, which leads to the opening of the jaw to more than 100 degrees. This ability allows them to consume extremely large prey, often 50% greater than their standard length.
The stoplight loosejaws are small, deep-sea dragonfishes of the genus Malacosteus, classified either within the subfamily Malacosteinae of the family Stomiidae, or in the separate family Malacosteidae. They are found worldwide, outside of the Arctic and Subantarctic, in the mesopelagic zone below a depth of 500 meters. This genus once contained three nominal species: M. niger, M. choristodactylus, and M. danae, with the validity of the latter two species being challenged by different authors at various times. In 2007, Kenaley examined over 450 stoplight loosejaw specimens and revised the genus to contain two species, M. niger and the new M. australis.
Argyropelecus hemigymnus, the half-naked hatchetfish, short silver hatchetfish or spurred hatchetfish, is a deep-sea hatchetfish of the genus Argyropelecus found mesopelagically in the Atlantic, Indian, and Pacific Oceans as well as in the Mediterranean Sea. It is a small species rarely exceeding 38 millimetres (1.5 in) standard length. It feeds on zooplankton, particularly ostracods and copepods. Sexual maturation occurs at length of about 22 mm, and adult males have more developed olfactory organs than females, i.e. the species is sexually dimorphic.
Lightfishes are small stomiiform fishes in the family Phosichthyidae
Sloane's viperfish, Chauliodus sloani, is a predatory mesopelagic dragonfish found in waters across the world. The species was first described by German scientists Marcus Elieser Bloch and Johann Gottlob Schneider in their 1801 book Systema ichthyologiae: iconibus CX illustratum, volume 1. Female C. sloani reach maturity between 133 and 191 mm, while males likely reach maturity at slightly smaller body lengths. It has two rows of photophores along its ventral side. It is believed that C. sloani can adjust the intensity of bioluminescence of the ventral photophores to camouflage itself from predators that might see its shadow from below.
The veiled anglemouth, Cyclothone microdon, is a bristlemouth of the family Gonostomatidae, abundant in all the world's oceans at depths of 300 – 2,500 meters. Its length is 10–15 cm (4–8 in) though the largest known specimen is 7.6 cm (3 in). It gets its name from its circular mouth, filled with small teeth: the name “cyclothone” means in a circle or around and “microdon” means small teeth. The International Union for Conservation of Nature (IUCN) has assessed the veiled anglemouth is of Least Concern due to its abundance in most oceans and the little effect human impact has on its population growth. Some of the veiled anglemouth's physical features include a brown to black body with a radiating, or expansive, bioluminescent pigment over its head and fins.
Cyclothone is a genus containing 13 extant species of bioluminescent fish, commonly known as 'bristlemouths' or 'bristlefishes' due to their shared characteristic of sharp, bristle-like teeth. These fishes typically grow to around 1-3 inches, though some can be larger. They are most commonly found in the mesopelagic zone of the ocean, mostly at depths of over 300 meters, and many species have bioluminescence.
Bonapartia pedaliota, the longray fangjaw, is a species of bristlemouth found in the Atlantic and Indian Oceans. It is the only described species in its genus. This species grows to a length of 7.2 centimetres (2.8 in) SL.
Gonostoma is a genus of bristlemouths.
Aristostomias is a genus of barbeled dragonfishes native to the ocean depths in the Pacific, Atlantic and Indian oceans.
Pachystomias microdon, the smalltooth dragonfish, is a species of barbeled dragonfish found in the oceans at depths of from 660 to 4,000 metres. This species grows to a length of 22.1 centimetres (8.7 in) SL. This species is the only known species in its genus.
