The Atheriniformes, also known as the silversides, are an order of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

es that includes the Old World silversides and several less-familiar families, including the unusual

Phallostethidae Phallostethidae, also known as the priapium fish, is a family of atheriniform fish native to freshwater and brackish habitats in southeast Asia. They are small, no more than in length, with partially translucent bodies. They are found in fresh ...

. The order includes at least 354 species. They are found worldwide in tropical and temperate marine and freshwater environments.

Description

Atheriniformes are generally elongated and silvery in colour, although exceptions do exist. They are typically small fish, with the largest being the Argentinian silverside, with a head-body length of , and the smallest species, such as the Bangkok minnow, being only in adult length. Members of the order usually have two

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s, the first with flexible spines, and an

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

with one spine at the front. The

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

is typically weak or absent. Atheriniform larvae share several characteristics; the gut is unusually short, a single row of

melanophore Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in cont ...

s occurs along the back, and the fin rays do not become evident until some time after hatching. They scatter their eggs widely, with most species attaching them to aquatic plants.

Taxonomy

Classification of the Atheriniformes is uncertain, with the best evidence for

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...

in the larval characteristics mentioned below. Their closest relatives are thought to be the

Cyprinodontiformes Cyprinodontiformes is an order of ray-finned fish, comprising mostly small, freshwater fish. Many popular aquarium fish, such as killifish and live-bearers, are included. They are closely related to the Atheriniformes and are occasionally inc ...

. Nelson 2016 recognizes the infraseries Atherinomorpha, part of the sub series

Ovalentaria Ovalentaria is a clade of ray-finned fishes within the Percomorpha, referred to as a subseries. It is made up of a group of fish families which are referred to in ''Fishes of the World's'' fifth edition as'' incertae sedis'', as well as the order ...

which includes the orders Atheriniformes,

Beloniformes Beloniformes is an order composed of six families (and about 264 species) of freshwater and marine ray-finned fish: * Adrianichthyidae (ricefish and medakas) * Belonidae (needlefish) * Exocoetidae (flyingfishes) * Hemiramphidae (halfbeaks) ...

, and Cyprinodontiformes, citing the larval characteristics and supporting molecular studies of these taxa as support for monophyly of this grouping. The sister taxon to the Atherinomorpha appears to be the

Mugiliformes The mullets or grey mullets are a family (Mugilidae) of ray-finned fish found worldwide in coastal temperate and tropical waters, and some species in fresh water. Mullets have served as an important source of food in Mediterranean Europe since R ...

. Following Nelson (2006), the family

Melanotaeniidae The rainbowfish or Melanotaeniidae is a family of small, colourful freshwater fish found in northern and eastern Australia, New Guinea (including islands in Cenderawasih Bay and Raja Ampat Islands in Indonesia), Sulawesi and Madagascar. The ...

includes the subfamilies Bedotiinae, Melanotaeniinae, Pseudomugilinae, and Telmatherininae, to demonstrate their

. However, in a 2004 study, a different classification scheme classifies the families Bedotiidae, Melanotaeniidae, and Pseudomugilidae (also include Telmatherinine genera) in a suborder Melanotaenioidei. Thus, the number of families in Atheriniformes varies from author to author. Nelson 2016 classifies the families as follows: * Order Atheriniformes ** Suborder Atherinopsoidei *** Family Atherinopsidae (New World silversides) *** Family

Notocheiridae The surf silverside (''Notocheirus hubbsi'') is a species of Silverside (fish), silverside from the Order (biology), order Atheriniformes found along the Pacific Ocean, Pacific coast of Argentina and Chile. It is the only known member of its Fam ...

(Surf silversides) ** Suborder

Atherinoidei Atherinoidei is a suborder of the order Atheriniformes comprising six families, with a mainly Old World distribution, although a few species are found in the western Atlantic Ocean. Families The suborder contains the following families: * ...

*** Family

Isonidae ''Iso'' is an Indo-Pacific genus of silversides, commonly called surf sardines, the only genus in the monogeneric family Isonidae, they were formerly classified in the family Notocheiridae alongside the surf silverside but they are now tho ...

(Surf sardines) *** Family

(Rainbowfishes and blue eyes) *** Family Atherionidae (Pricklenose silversides) *** Family Dentatherinidae (Mercer's tusked silverside) *** Family

(Priapiumfishes) *** Family

Atherinidae The Old World silversides are a family, Atherinidae, of fish in the order Atheriniformes. Atherinidae are abundant and considered bony fish (teleost) that are widespread globally, living in rivers, estuaries, and coastal waters. They occur worl ...

(Old World silversides)

Timeline of genera

ImageSize = width:1000px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-65.5 till:15 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:5 start:-65.5 ScaleMinor = unit:year increment:1 start:-65.5 TimeAxis = orientation:hor AlignBars = justify Colors = #legends id:CAR value:claret id:ANK value:rgb(0.4,0.3,0.196) id:HER value:teal id:HAD value:green id:OMN value:blue id:black value:black id:white value:white id:cenozoic value:rgb(0.54,0.54,0.258) id:paleogene value:rgb(0.99,0.6,0.32) id:paleocene value:rgb(0.99,0.65,0.37) id:eocene value:rgb(0.99,0.71,0.42) id:oligocene value:rgb(0.99,0.75,0.48) id:neogene value:rgb(0.999999,0.9,0.1) id:miocene value:rgb(0.999999,0.999999,0) id:pliocene value:rgb(0.97,0.98,0.68) id:quaternary value:rgb(0.98,0.98,0.5) id:pleistocene value:rgb(0.999999,0.95,0.68) id:holocene value:rgb(0.999,0.95,0.88) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM2 bar:NAM3 bar:NAM4 bar:NAM5 bar:NAM6 bar:NAM7 bar:NAM8 bar:NAM9 bar:space bar:period bar:space bar:era PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 shift:(7,-4) bar:periodtop from: -65.5 till: -55.8 color:paleocene text:

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

from: -55.8 till: -33.9 color:eocene text:

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

from: -33.9 till: -23.03 color:oligocene text:

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

from: -23.03 till: -5.332 color:miocene text:

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

from: -5.332 till: -2.588 color:pliocene text: Plio. from: -2.588 till: -0.0117 color:pleistocene text:

Pleist. The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

from: -0.0117 till: 0 color:holocene text: H. bar:eratop from: -65.5 till: -23.03 color:paleogene text:

Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

from: -23.03 till: -2.588 color:neogene text:

Neogene The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. ...

from: -2.588 till: 0 color:quaternary text: Q. PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left color:eocene bar:NAM1 from:-55.8 till:0 text:

Atherina ''Atherina'' is a genus of fish of silverside family Atherinidae, found in the temperate and tropic zones. Up to 15 cm long, they are widespread in the Mediterranean, Black Sea, Sea of Azov in lagoons and estuaries. It comes to the low stre ...

color:eocene bar:NAM2 from:-37.2 till:-5.332 text: Palaeoatherina color:eocene bar:NAM3 from:-37.2 till:0 text: Pranesus color:miocene bar:NAM4 from:-23.03 till:0 text:

Stenatherina The panatela silverside (''Hypoatherina panatela'') is a species of reef-dwelling old world silverside, silverside from the subfamily Atherinomorinae which is found in the southwest Pacific Ocean. This species grows to in fish measurement, total ...

color:miocene bar:NAM5 from:-11.608 till:0 text: Atherinopsis color:pliocene bar:NAM6 from:-5.332 till:0 text:

Chirostoma ''Chirostoma'' is a genus of Neotropical silversides from the Lerma River basin in Mexico, including lakes Chapala and Pátzcuaro. Fish in the genus collectively go by the common name charal/charales in their native range (a name also used for ...

color:pliocene bar:NAM7 from:-5.332 till:0 text:

Colpichthys ''Colpichthys'' is a genus of Neotropical silverside endemic to the Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilio ...

color:pliocene bar:NAM8 from:-5.332 till:0 text:

Menidia ''Menidia'' is a genus of Neotropical silversides native to freshwater, brackish and marine habitats along the Atlantic and Gulf of Mexico coasts of North America, ranging from the Gulf of Saint Lawrence in Canada to the Yucatán Peninsula in Mex ...

color:pleistocene bar:NAM9 from:-2.588 till:0 text:

Leuresthes Grunion are two fish species of the genus ''Leuresthes'': the California grunion, ''L. tenuis'', and the Gulf grunion, ''L. sardinas''. They are sardine-sized teleost fishes of the New World silverside family Atherinopsidae, found only off t ...

PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -65.5 till: -55.8 color:paleocene text:

from: -55.8 till: -33.9 color:eocene text:

from: -33.9 till: -23.03 color:oligocene text:

from: -23.03 till: -5.332 color:miocene text:

from: -5.332 till: -2.588 color:pliocene text: Plio. from: -2.588 till: -0.0117 color:pleistocene text:

from: -0.0117 till: 0 color:holocene text: H. bar:era from: -65.5 till: -23.03 color:paleogene text:

from: -23.03 till: -2.588 color:neogene text:

from: -2.588 till: 0 color:quaternary text: Q.

References

* {{taxonbar, from=Q254606 Ray-finned fish orders Articles which contain graphical timelines