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.
Barracudinas are any member of the marine mesopelagic fish family Paralepididae: 50 or so extant species are found almost worldwide in deep waters. Several genera are known only from fossils dating back to the Ypresian epoch.
Aulopiformes is a diverse order of marine ray-finned fish consisting of some 15 extant and several prehistoric families with about 45 genera and over 230 species. The common names grinners, lizardfishes and allies, or aulopiforms are sometimes used for this group. The scientific name means "Aulopus-shaped", from Aulopus + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek aulós + Latin forma, the former in reference to the elongated shape of many aulopiforms.
Marine hatchetfishes or deep-sea hatchetfishes are small deep-sea mesopelagic ray-finned fish of the stomiiform subfamily Sternoptychinae. They should not be confused with the freshwater hatchetfishes, which are not particularly closely related Teleostei in the characiform family Gasteropelecidae.
Cetomimidae is a family of small, deep-sea cetomimiform fish. They are among the most deep-living fish known, with some species recorded at depths in excess of 3,500 m (11,500 ft). Females are known as flabby whalefishes, Males are known as bignose fishes, while juveniles are known as tapetails and were formerly thought to be in a separate family, dubbed Mirapinnidae. Adults exhibit extreme sexual dimorphism, and the adult males were once thought to be exemplars of still another family, Megalomycteridae.
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.
Lancetfishes are large oceanic predatory fishes in the genus Alepisaurus in the monogeneric family Alepisauridae.
Leftvents are small, deep-sea lophiiform fish comprising the family Linophrynidae distributed throughout tropical to subtropical waters of all oceans.
Sabertooth or sabretooth fish are small, fierce-looking deep-sea aulopiform fish comprising the family Evermannellidae. The family is small, with just eight species in three genera represented; they are distributed throughout tropical to subtropical waters of the Atlantic, Indian, and Pacific Oceans.
Barreleyes, also known as spook fish, are small deep-sea argentiniform fish comprising the family Opisthoproctidae found in tropical-to-temperate waters of the Atlantic, Pacific, and Indian Oceans.
The Zeidae are a family of large, showy, deep-bodied zeiform marine fish—the "true dories". Found in the Atlantic, Indian, and Pacific Oceans, the family contains just six species in two genera. All species are important and highly regarded food fish supporting commercial fisheries, and some—such as the John Dory —are enjoyed in large public aquaria. These fish are caught primarily by deep-sea trawling.
Ridgeheads, also known as bigscales, are a family of small, deep-sea stephanoberyciform fish. The family contains approximately 37 species in five genera; their distribution is worldwide, but ridgeheads are absent from the Arctic Ocean and Mediterranean Sea. Although the family is one of the most widespread and plentiful of deep-sea families, none of its members are of interest to commercial fishery.
The black swallower is a species of deep sea fish in the family Chiasmodontidae. It is known for its ability to swallow fish larger than itself.
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.
Haplophryne mollis, the ghostly seadevil or soft leftvent angler, is a species of anglerfish in the family Linophrynidae and is the only species in the genus Haplophryne. It is found in the bathypelagic and mesopelagic zones of tropical and subtropical parts of the world's oceans at depths down to about 2,250 m (7,400 ft).
The daggertooths are a genus of marine mesopelagic fish in the order Aulopiformes, the sole genus of the family Anotopteridae. They are found in oceans worldwide, but prefer cooler waters.
Bathypterois is a genus of deepsea tripod fishes. They are a diverse genus that belong to the greater family Ipnopidae and order Aulopiformes. They are distinguished by having two elongated pelvic fins and an elongated caudal fin, which allow them to move and stand on the ocean floor, much like a tripod, hence the common name. Bathypterois are distributed worldwide with some particular species of the genus having specialized environmental niches, such as lower dissolved oxygen concentrations. Bathypterois have a reduced eye size, highly specified extended fins, and a mouth adapted to filter feeding. They are filter feeders whose main food source is benthopelagic planktonic calanoid copepods, but some variation is seen with maturity in secondary food sources. Bathypterois use their three elongated fins for a wide range of motion from landing to standing on the ocean floor to catching prey, for which these fins serve as specialized perceptory organs. Bathypterois have both male and female gonads at once making, them simultaneous hermaphrodites, whose gonads go through five stages of development following seasonal autumn spawning.
Lampris guttatus, commonly known as the opah, cravo, moonfish, kingfish, and Jerusalem haddock, is a large, colorful, deep-bodied pelagic lampriform fish belonging to the family Lampridae, which comprises the genus Lampris.
Taractichthys steindachneri, the sickle pomfret, is a species of marine ray-finned fish, a pomfret of the family Bramidae. It is found in the Indian and Pacific Oceans.
Caulophryne pelagica is a species of marine ray-finned fish belonging to the family Caulophrynidae, the fanfins. This species is a deepwater species which is found in the eastern Atlantic, Indian Ocean, Pacific Ocean and Southern Ocean. Its biology is little known but similar species show extreme sexual dimorphism with the very small makes seeking out and attaching themselves to the much larger females and becoming parasites of the females.
