Slimehead
Encyclopedia
Slimeheads, also known as roughies and redfish, are mostly small, exceptionally long-lived, deep-sea beryciform fish
constituting the family
Trachichthyidae (derived from the Greek
trachys ["rough"] and ichthys ["fish"]). Found in temperate to tropical waters of the Atlantic
, Indian
, and Pacific Ocean
, the family comprises approximately 45 species
in eight genera
. Slimeheads are named for the network of muciferous
canals riddling their heads.
The larger species — namely the orange roughy
(Hoplostethus atlanticus) and Darwin's slimehead (Gephyroberyx darwinii) — are the target of extensive commercial fisheries
off Australia
and New Zealand
. Many populations have already crashed, while others are showing signs of severe overfishing
; due to slimeheads' slow rate of reproduction, the future viability of these fisheries has been put into question. Orange roughies are food fish and are marketed fresh and frozen, whereas Darwin's slimeheads are utilised for their oil
and made into fishmeal.
s, and (in some species) bright colours. The head is especially notable for its network of mucus-filled canals, which constitute the cranial portion of the lateral line
system. Similar cranial networks are found in the beryciform fangtooth
s (Anoplogastridae) and the stephanoberyciform
ridgehead
s (Melamphaidae). The trachichthyid head is typically blunt with a large and oblique mouth
; the snout may project slightly in front of the upper jaw. A short, sharp spine
is present on the preoperculum
and/or operculum
and posttemporal bone
, the latter spine directed posteriorly. Species of the genera Optivus, Paratrachichthys, and Sorosichthys differ in form from other members of the family; their bodies are more elongate.
All fin
s are spinous (excluding the low-slung pectoral fins) and rounded: there is a single dorsal fin
with 3–8 spines and 10–19 soft rays; the pelvic fins are thoracic with one spine and 6–7 soft rays; the anal fin has 2–3 spines and 8–12 soft rays; and even the forked caudal fin possesses 4–7 procurrent spines on each lobe. The scales of slimeheads are ctenoid but vary interspecifically; they range from deciduous to adherent. In most species the ventral scales between the pelvic fin and anus
have been modified into a median ridge of large, bony scute
s. The lateral line
is uninterrupted and fairly obvious; its pores are largely obscured by the scales' well-developed spinules or ctenii.
Slimeheads range from a bright brick red with identically shaded fins, to dusky grey or silver, to black with dusky grey to transparent fins. The reds quickly fade to orange following death. Some species (e.g., Aulotrachichthys latus) are reported to be bioluminescent
, probably via symbiotic
bacteria as is found in other beryciform fish. The largest species is the orange roughy at a maximum standard length (SL; a measurement excluding the caudal fin) of 75 cm and a weight of 7 kg; however, most slimeheads are well under 30 cm SL.
, spending most of their time near the bottom of continental slopes. Cold, moderate benthopelagic
depths (ca. 100 – 1,500 m) with usually hard, rocky substrates are frequented. The most elongate species are typically the most active and frequent the shallowest depths; for example, the slender roughy
(Optivus elongatus) is found in photic
coastal waters and is associated with rocky reef
s. This species is nocturnal and hides in crevices during the day. Trachichthys australis is of the same habitus, but is rather deep-bodied and resembles a soldierfish
. Both young and adult slimeheads feed primarily upon zooplankton
such as mysid shrimp
, amphipods, euphausiids, prawn
s and other crustacean
s, as well as larva
l fish. Slimeheads store energy as extracellular
wax
ester
s, which aid the fish in maintaining neutral buoyancy
.
Slimehead behaviour is not well studied, but some species sporadically form dense aggregations. In the case of the orange roughy, these aggregations (possibly segregated according to sex) may reach a population density of 2.5/m²;. The aggregations form in and around geologic structures, such as undersea canyon
s and seamount
s, likely where water movement and mixing is high, ensuring dense concentrations of prey items. The aggregations do not necessarily form for the purpose of spawning; it is thought that the fish cycle through metabolic
phases (feeding and resting) and seek areas with ideal hydrologic
conditions to congregate during their inactive and active phases. Observations of orange roughy aggregations during submersible dives have also shown that the fish lose almost all pigmentation while inactive, during which time they are very approachable. The orange roughy's metabolic phases are thought to be related to seasonal variations in the fishes' prey concentrations, with the inactive phase being a means to conserve energy during lean periods.
Slimeheads are non-guarding pelagic spawner
s; that is, spawning aggregations are formed and the fish release eggs
and sperm
en masse directly into the water. There is evidence of oceanodromy (seasonal migration
) in some species. The fertilized eggs (and later the larvae) are plankton
ic, floating with the currents until the larvae develop the strength to determine their own way. Only the economically important species have had their reproduction studied in any detail: the larvae and juveniles of Darwin's slimehead are pelagic and frequent rather shallow waters near the coast, whereas in orange roughy the early life stages are apparently confined to deeper water (ca. 200 metres). Slimeheads are very slow-growing and long-lived fish; the orange roughy ranks among the longest-lived animals known, with a maximum reported age of 149 years (however, this age is disputed). Predators of slimeheads are not well known, but include large deep-roving shark
s; cutthroat eel
s; merluccid hakes, and snake mackerel
s.
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
constituting the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Trachichthyidae (derived from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
trachys ["rough"] and ichthys ["fish"]). Found in temperate to tropical waters of the Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, and Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, the family comprises approximately 45 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in eight genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. Slimeheads are named for the network of muciferous
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
canals riddling their heads.
The larger species — namely the orange roughy
Orange roughy
The orange roughy, red roughy, or deep sea perch, Hoplostethus atlanticus, is a relatively large deep-sea fish belonging to the slimehead family . The Marine Conservation Society has categorized orange roughy as vulnerable to exploitation...
(Hoplostethus atlanticus) and Darwin's slimehead (Gephyroberyx darwinii) — are the target of extensive commercial fisheries
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
off Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
. Many populations have already crashed, while others are showing signs of severe overfishing
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
; due to slimeheads' slow rate of reproduction, the future viability of these fisheries has been put into question. Orange roughies are food fish and are marketed fresh and frozen, whereas Darwin's slimeheads are utilised for their oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
and made into fishmeal.
Physical description
With a typically deep-bodied, laterally compressed form, slimeheads are conspicuous for their large, titular heads, large eyeEye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
s, and (in some species) bright colours. The head is especially notable for its network of mucus-filled canals, which constitute the cranial portion of the lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
system. Similar cranial networks are found in the beryciform fangtooth
Fangtooth
Fangtooths are beryciform fish of the family Anoplogastridae that live in the deep sea. The name is from Greek anoplo meaning "unarmed" and gaster meaning "stomach"...
s (Anoplogastridae) and the stephanoberyciform
Stephanoberyciformes
The Stephanoberyciformes are an order of marine ray-finned fishes, consisting of about 45 species, the majority of which belong to the ridgehead family . The Stephanoberyciformes are mostly uncommon deep-sea species with little, if any, importance to commercial fishery...
ridgehead
Ridgehead
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...
s (Melamphaidae). The trachichthyid head is typically blunt with a large and oblique mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
; the snout may project slightly in front of the upper jaw. A short, sharp spine
Spine (zoology)
A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin...
is present on the preoperculum
Operculum (fish)
The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....
and/or operculum
Operculum (fish)
The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body....
and posttemporal bone
Temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...
, the latter spine directed posteriorly. Species of the genera Optivus, Paratrachichthys, and Sorosichthys differ in form from other members of the family; their bodies are more elongate.
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...
s are spinous (excluding the low-slung pectoral fins) and rounded: there is a single dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
with 3–8 spines and 10–19 soft rays; the pelvic fins are thoracic with one spine and 6–7 soft rays; the anal fin has 2–3 spines and 8–12 soft rays; and even the forked caudal fin possesses 4–7 procurrent spines on each lobe. The scales of slimeheads are ctenoid but vary interspecifically; they range from deciduous to adherent. In most species the ventral scales between the pelvic fin and anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
have been modified into a median ridge of large, bony scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
s. The lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
is uninterrupted and fairly obvious; its pores are largely obscured by the scales' well-developed spinules or ctenii.
Slimeheads range from a bright brick red with identically shaded fins, to dusky grey or silver, to black with dusky grey to transparent fins. The reds quickly fade to orange following death. Some species (e.g., Aulotrachichthys latus) are reported to be bioluminescent
Bioluminescence
Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...
, probably via symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
bacteria as is found in other beryciform fish. The largest species is the orange roughy at a maximum standard length (SL; a measurement excluding the caudal fin) of 75 cm and a weight of 7 kg; however, most slimeheads are well under 30 cm SL.
Life history
Most slimeheads are sluggish and demersalBenthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
, spending most of their time near the bottom of continental slopes. Cold, moderate benthopelagic
Pelagic zone
Any water in a sea or lake that is not close to the bottom or near to the shore can be said to be in the pelagic zone. The word pelagic comes from the Greek πέλαγος or pélagos, which means "open sea". The pelagic zone can be thought of in terms of an imaginary cylinder or water column that goes...
depths (ca. 100 – 1,500 m) with usually hard, rocky substrates are frequented. The most elongate species are typically the most active and frequent the shallowest depths; for example, the slender roughy
Slender roughy
The slender roughy, Optivus elongatus, is a small slimehead of the family , the only member of the genus Optivus, found in the western Pacific Ocean around Australia and New Zealand at depths of between 1 and 100 m...
(Optivus elongatus) is found in photic
Photic zone
The photic zone or euphotic zone is the depth of the water in a lake or ocean that is exposed to sufficient sunlight for photosynthesis to occur...
coastal waters and is associated with rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s. This species is nocturnal and hides in crevices during the day. Trachichthys australis is of the same habitus, but is rather deep-bodied and resembles a soldierfish
Holocentridae
The Holocentridae is a family of ray-finned fish, belonging to the order Beryciformes with the members of the subfamily Holocentrinae typically known as squirrelfish, while the members of Myripristinae typically are known as soldierfish...
. Both young and adult slimeheads feed primarily upon zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
such as mysid shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, amphipods, euphausiids, prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
s and other crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, as well as larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
l fish. Slimeheads store energy as extracellular
Extracellular
In cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...
wax
Wax
thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...
ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s, which aid the fish in maintaining neutral buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
.
Slimehead behaviour is not well studied, but some species sporadically form dense aggregations. In the case of the orange roughy, these aggregations (possibly segregated according to sex) may reach a population density of 2.5/m²;. The aggregations form in and around geologic structures, such as undersea canyon
Canyon
A canyon or gorge is a deep ravine between cliffs often carved from the landscape by a river. Rivers have a natural tendency to reach a baseline elevation, which is the same elevation as the body of water it will eventually drain into. This forms a canyon. Most canyons were formed by a process of...
s and seamount
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
s, likely where water movement and mixing is high, ensuring dense concentrations of prey items. The aggregations do not necessarily form for the purpose of spawning; it is thought that the fish cycle through metabolic
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
phases (feeding and resting) and seek areas with ideal hydrologic
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
conditions to congregate during their inactive and active phases. Observations of orange roughy aggregations during submersible dives have also shown that the fish lose almost all pigmentation while inactive, during which time they are very approachable. The orange roughy's metabolic phases are thought to be related to seasonal variations in the fishes' prey concentrations, with the inactive phase being a means to conserve energy during lean periods.
Slimeheads are non-guarding pelagic spawner
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
s; that is, spawning aggregations are formed and the fish release eggs
Roe
Roe or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals, such as shrimp, scallop and sea urchins...
and sperm
Spermatozoon
A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote...
en masse directly into the water. There is evidence of oceanodromy (seasonal migration
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
) in some species. The fertilized eggs (and later the larvae) are plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic, floating with the currents until the larvae develop the strength to determine their own way. Only the economically important species have had their reproduction studied in any detail: the larvae and juveniles of Darwin's slimehead are pelagic and frequent rather shallow waters near the coast, whereas in orange roughy the early life stages are apparently confined to deeper water (ca. 200 metres). Slimeheads are very slow-growing and long-lived fish; the orange roughy ranks among the longest-lived animals known, with a maximum reported age of 149 years (however, this age is disputed). Predators of slimeheads are not well known, but include large deep-roving shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s; cutthroat eel
Cutthroat eel
Cutthroat eels are a family, Synaphobranchidae, of eels, the only member of the suborder Synaphobranchoidei. They are found worldwide in temperate and tropical seas....
s; merluccid hakes, and snake mackerel
Snake mackerel
Gempylidae is a family of perciform fishes, commonly known as snake mackerels or escolars.They are elongate fishes with a similar appearance to barracudas, having a long dorsal fin, usually with one or finlets trailing it. The largest species, including the snoek, Thyrsites atun, grow up to two...
s.
Species
There are 45 species in eight genera:- Genus Aulotrachichthys
- Aulotrachichthys latus (Fowler, 1938).
- Genus Gephyroberyx
- Darwin's slimehead, Gephyroberyx darwinii (Johnson, 1866).
- Gephyroberyx japonicus (Hilgendorf, 1879).
- Gephyroberyx philippinus Fowler, 1938.
- Genus Hoplostethus
- Hoplostethus abramovi Kotlyar, 1986.
- Orange roughyOrange roughyThe orange roughy, red roughy, or deep sea perch, Hoplostethus atlanticus, is a relatively large deep-sea fish belonging to the slimehead family . The Marine Conservation Society has categorized orange roughy as vulnerable to exploitation...
, Hoplostethus atlanticus Collett, 1889. - Black slimehead, Hoplostethus cadenati Quéro, 1974.
- Hoplostethus confinis Kotlyar, 1980.
- Hoplostethus crassispinus Kotlyar, 1980.
- Hoplostethus druzhinini Kotlyar, 1986.
- Hoplostethus fedorovi Kotlyar, 1986.
- Hoplostethus fragilis (de Buen, 1959).
- Hoplostethus gigas McCulloch, 1914.
- Hoplostethus intermedius (Hector, 1875).
- Flintperch, Hoplostethus japonicus Hilgendorf, 1879.
- Giant sawbelly, Hoplostethus latus (Fowler, 1938).
- Hoplostethus marisrubri Kotlyar, 1986.
- Mediterranean slimehead, Hoplostethus mediterraneus mediterraneus CuvierGeorges CuvierGeorges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
, 1829.
- Hoplostethus mediterraneus sonodae Kotylar, 1986.
- Silver roughySilver roughyThe silver roughy, Hoplostethus mediterraneus trunovi, is a small deep-sea fish subspecies belonging to the slimehead family found in cold , deep waters of the western Indian Ocean....
, Hoplostethus mediterraneus trunovi Kotylar, 1986. - Hoplostethus melanopterus Fowler, 1938.
- Smallscale slimehead, Hoplostethus melanopus (Weber, 1913).
- Hoplostethus mento (Garman, 1899).
- Hoplostethus metallicus Fowler, 1938.
- Hoplostethus mikhailini Kotlyar, 1986.
- Hoplostethus occidentalis Woods, 1973.
- Hoplostethus pacificus Garman, 1899.
- Hoplostethus rifti Kotlyar, 1986.
- Hoplostethus rubellopterus Kotlyar, 1980.
- Hoplostethus shubnikovi Kotlyar, 1980.
- Hoplostethus tenebricus Kotlyar, 1980.
- Hoplostethus vniro Kotlyar, 1995.
- Genus Optivus
- Slender roughySlender roughyThe slender roughy, Optivus elongatus, is a small slimehead of the family , the only member of the genus Optivus, found in the western Pacific Ocean around Australia and New Zealand at depths of between 1 and 100 m...
, Optivus elongatus (Günther, 1859).
- Slender roughy
- Genus Paratrachichthys
- Paratrachichthys argyrophanus Woods, 1961.
- Paratrachichthys atlanticus (Collett, 1889).
- Paratrachichthys fernandezianus (Günther, 1887).
- Paratrachichthys heptalepis Gon, 1984.
- Paratrachichthys novaezelandicus Kotlyar, 1980.
- Paratrachichthys prosthemius JordanDavid Starr JordanDavid Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...
& Fowler, 1902. - Paratrachichthys pulsator (Gomon & KuiterRudie KuiterRudie Kuiter is an Australian underwater photographer, taxonomist, and marine biologist. He has described many new species of seahorse.He was born in the Netherlands.-Publications:* Photo Guide to Fishes of the Maldives by Rudie H. Kuiter...
, 1987). - Paratrachichthys sajademalensis Kotlyar, 1979.
- Sandpaper fishSandpaper fishThe sandpaper fish or common roughy, Paratrachichthys trailli, is a slimehead belonging to the family Trachichthyidae, found in southern Australia and southern New Zealand at depths of between 50 and 400 m...
or common roughy, Paratrachichthys trailli (Hutton, 1875).
- Genus Parinoberyx
- Parinoberyx horridus Kotlyar, 1984.
- Genus Sorosichthys
- Little pineapple fishLittle pineapple fishThe little pineapple fish, Sorosichthys ananassa, is a small slimehead of the family Trachichthyidae, the only member of the genus Sorosichthys, found in the eastern Indian Ocean, on the continental shelf of the southwestern coasts of Western Australia and South Australia, at depths of between 50...
, Sorosichthys ananassa Whitley, 1945.
- Little pineapple fish
- Genus Trachichthys
- Trachichthys australis Shaw, 1799.