General description Brief description of the body form and size, recognisable attributes Why do scientists study these organisms and why are they important to the public at large (e.g. important to CCAMLR policy-makers) Why are they included in MEASO? Midwater fishes are those species that occupy mesopelagic depths (~200-1000 m) in the water column. Midwater fishes can be highly abundant, comprising up to 95% of total catches, which have been reported to comprise over 2000 species and representing 19 taxonomic families in one study (Miya et al. 1986), although more have been recorded globally and throughout the Southern Ocean (Duhamel et al. 2014). In the Southern Ocean, among the most abundant of the midwater fishes are members of the Myctophidae, Gonostomatidae, and Bathylagidae families, however this page will focus on the latter two (information on Myctophids is presented here).
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| Summarise taxa included in this group (Classification if available) Taxonomy Classification: Kingdom Animalia Phylum Chordata Class Actinopterygii Orders Alepocephaliformes, Anguilliformes, Argentiniformes, Aulopiformes, Beryciformes, Cetomimiformes, Gadiformes, Lampridiformes, Lophiiformes, Osmeriformes, Scombriformes, Stomiiformes, Trachiniformes | Family | Description | Species | Image |
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| Alepisauridae | Lancetfishes that can grow up to 2 m in length | Alepisaurus brevirostris Gibbs, 1960 |
| | Anotopteridae | Family of mesopelagic fishes also known as daggertooths that possess sharp teeth and elongated bodies that lack scales. | Anotopterus vorax Regan, 1913 |
| | Bathylagidae | Known commonly as deep-sea smelts, they are small sized planktivores and have been reported at depths of up to 1500 m. Five species have been reported in the Southern Ocean (Duhamel et al. 2014). | Bathylagichthys australis Koyliansky, 1990 Bathylagus antarcticus Günther, 1878 Bathylagus gracilis Lönnberg, 1905 Bathylagus niger Kobyliansky, 2006 Bathylagus tenuis Kobyliansky, 1986 |  Image Added
Image ©Tony Ayling | | Ceratiidae | Commonly referred to as sea devils, they are anglerfish that possess a bioluminescent lure projecting from its forehead and used to attract prey. Their elongated bodies can reach 1.2 m in length, with females being larger than males. After a free-living adolescent stage, one or more males spend the rest of their lives attached to a female, eventually merging circulatory systems. | Ceratias tentaculatus Norman, 1930 |
| | Cetomimidae | Small-sized fishes collectively known as flabby whalefish, with adults exhibiting distinct sexual dimorphism. They are found throughout the Southern Hemisphere. | Gyrinomimus andriashevi Fedorov, Balushkin & Trunov, 1987 Gyrinomimus grahami Richardson & Garrick, 1964 Notocetichthys trunovi Balushkin, Fedorov & Paxton, 1989 |
| | Chiasmodontidae | Commonly known as snaketooth fishes and have a cosmopolitan distribution. | Chiasmodon niger Johnson, 1864 Kali sp. (see Hanchet et al., 2013) Pseudoscopelus altipinnis Parr, 1933 |
| | Gadidae | Medium-sized family of fishes known collectively as cods, codfishes, or true cods, many of which are commercially harvested. They are carnivorous, and prefer to eat smaller-sized fish and crustaceans. | Micromesistius australis Norman, 1937 |
| | Gigantactinidae | Known commonly as a whipnose angler, they protrude exceptionally long lures (illicium) which may be longer than their body length. | Gigantactis sp. (see Hanchet et al., 2013) |
| | Gonostomatidae | Commonly named bristlemouths, lightfishes, and/or anglemouths, they are a relatively small family wiht only 32 species known globally. In the Southern Ocean, this family has been reported as the most numerous (up to 72%) among total catches (Miya et al. 1986). | Cyclothone acclinidens Garman, 1899 Cyclothone braueri Cyclothone kobayashii Miya, 1994 Cyclothone microdon Günther, 1898 Cyclothone pallida Brauer, 1902 Diplophos rebainsi Krefft & Parin, 1972 Sigmops bathyphilus Vaillant, 1884 |  Image Added
Image © Steen Knudsen from iucnredlist.org | | Lampridae | Known as opah, the genus Lampris is derived from the Ancient Greek word lampros which means "brilliant" or "clear", likely referring to their colourful skin. Though not commercially targeted, they do represent an important component of commercial fishery (mostly tuna) as bycatch. Their prevalence is increasing in regions such as the Mediterranean and is believed to be a result of climate change (Francour et al. 2010). Lampris guttatus is reported to maintain an entire body temperature 5°C consistently above ambient temperature (Wegner et al. 2015). | Lampris immaculatus Brünnich, 1788 Lampris guttatus Gilchrist, 1904 |
| | Melamphaidae | Common names include ridgeheads and bigscales for their pronounced cranial ridges and large scales. They are small-size with a global distribution. | Melamphaes microps Günther, 1878 Poromitra crassiceps Günther, 1878 Sio nordenskjoldii Lönnberg, 1905 |
| | Melanonidae | Gadiform fish, small in size (15 m in length, maximum) and black in colour. | Melanonus gracilis Günther, 1878 |
| | Merlucciidae | Commonly known as hakes, they are a cold water fish, with body sizes averaging 1.55 m in length, and are found at depths greater than 50 m | Merluccius australis Hutton, 1872 |
| | Microstomatidae | Also referred to as pencil smelts, they are marine smelts found in Atlantic, Indian, and Pacific Oceans. | Nansenia antarctica Kawaguchi & Butler, 1984 |
| | Nemichthyidae | Cosmopolitan pelagic fishes commonly known as snipe eels. They can be found at 300-600 m depths, but sometimes reported up to 4000 m. Adults may reach 1-2 m in length. | Avocettina sp. (see Trunov, 1999) Labichthys yanoi Mead & Rubinoff, 1966 Nemichthys curvirostris Strömman, 1896 Nemichthys scolopaceus Richardson, 1848 |
| | Notosudidae | Commonly referred to as waryfishes with subarctic and subantarctic distributions. They possess teeth on their upper jaws and lack a swim bladder. | Luciosudis normani Fraser-Brunner, 1931 Scopelosaurus hamiltoni Waite, 1916 |
| | Oneirodidae | Known commonly as the dreamers, these are the largest and most biodiverse group of anglerfishes though small in size (maximum length approximately 20 cm). | Oneirodes notius Pietsch, 1974 |
| | Paralepididae | These barracudinas have elongated, slender bodies with pointed snout and elongated bodies. They have been reported at depths 200-1000 m; they prey on smaller fish, crustaceans and squid and are preyed upon by larger fishes such as tuna, lancetfish, blue sharks, as well as the mammalian Cuvier's beaked whales. | Arctozenus risso Bonaparte, 1840 Macroparalepis macrogeneion Post, 1973 Magnisudis prionosa Rofen, 1963 Notolepis annulata Post, 1978 Notolepis coatsi Dollo, 1908 |
| | Platytroctidae | These are a family of small to medium-sized (9 to 33 cm in length) marine smelts collectively known as tubeshoulders. They have been reported at depths 300-1000 m and possess light-producing organs. | Normichthys yahganorum Lavenberg, 1965 Sagamichthys abei Parr, 1953 |
| | Scombridae | Family includes mackerels, tunas, and bonitos, with the Butterfly mackerel and the Southern Bluefin tuna among the most common species found in the Southern Ocean. | Gasterochisma melampus Richardson, 1845 Thunnus maccoyii Castelnau, 1872 |
| | Scopelarchidae | Known also as pearleyes, they are small to medium-sized (3.7-35 cm in length) fishes that possess two retinas in each of their telescopic eyes which give them ability to see in almost complete darkness. | Benthalbella elongata Norman, 1937 Benthalbella macropinna Bussing & Bussing, 1966 |
| | Serrivomeridae | Commonly referred to as the sawtooth eel, found throughout temperate and tropical oceanic regions. | Serrivomer sp. (see Trunov, 1999) |
| | Sternoptychidae | Known commonly as hatchetfishes, they can be found at depths of 200-600 m throughout global temperate, tropical and subtropical oceans. They are capable of bioluminescent counter-illumination as a predator defence mechanism. | Argyropelecus aculeatus Valenciennes, 1850 Argyropelecus affinis Garman, 1899 Argyropelecus gigas Norman, 1930 Argyropelecus hemigymnus Cocco, 1829 Argyropelecus olfersii Cuvier, 1829 Maurolicus muelleri Gmelin, 1789 Sternoptyx diaphana Hermann, 1781 Sternoptyx pseudobscura Baird, 1971 Sternoptyx pseudodiaphana Borodulina, 1977 |
| | Stomiidae | Small-sized fishes (15 cm average length) consisting of ray-finned fish with large jaws with fang-like teeth. Can consume prey larger than half their body length with their ability to open their jaw wide by hinging the neurocranium and upper-jaw system. | Astronesthes psychrolutes Gibbs & Weitzman, 1965 Borostomias antarcticus Lönnberg, 1905 Chauliodus sloani Bloch & Schneider, 1801 Idiacanthus atlanticus Brauer, 1906 Stomias boa Risso, 1810 Stomias gracilis Garman, 1899 Trigonolampa miriceps Regan & Trewavas, 1930 |
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