The Atheriniformes, also known as the silversides, are an order of ray-finned fishes that includes the Old World silversides and several less-familiar families, including the unusual Phallostethidae.
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 jacksmelt, 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 fins, the first with flexible spines, and an anal fin with one spine at the front.
The lateral line is typically weak or absent.
Atheriniform larvae share several characteristics; the gut is unusually short, a single row of melanophores 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 the larval characteristics mentioned below.
Their closest relatives are thought to be the Cyprinodontiformes.
Nelson 2016 recognises the infraseries Atherinomorpha, part of the sub series Ovalentaria which includes the orders Atheriniformes, Beloniformes, 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.
Following Nelson (2006), the family Melanotaeniidae includes the subfamilies Bedotiinae, Melanotaeniinae, Pseudomugilinae, and Telmatherininae, to demonstrate their monophyly.
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 (Surf silversides)
Suborder Atherinoidei
Family Isonidae (Surf sardines)
Family Melanotaeniidae (Rainbowfishes and blue eyes)
Family Atherionidae (Pricklenose silversides)
Family Dentatherinidae (Mercer's tusked silverside)
Family Phallostethidae (Priapiumfishes)
Family Atherinidae (Old World silversides)
Timeline of genera
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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
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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
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bar:periodtop  from: -65.5   till:  -55.8    color:paleocene  text:[[Paleocene]]  from: -55.8   till:  -33.9    color:eocene  text:[[Eocene]]   from: -33.9   till:  -23.03    color:oligocene  text:[[Oligocene]]              from: -23.03    till: -5.332    color:miocene    text:[[Miocene]]  from: -5.332    till: -2.588    color:pliocene    text:[[Plio.]]  from: -2.588    till: -0.0117   color:pleistocene    text:[[Pleist.]]  from: -0.0117    till: 0    color:holocene    text:[[Holocene|H.]]
bar:eratop  from: -65.5   till:  -23.03    color:paleogene  text:[[Paleogene]]           from: -23.03    till: -2.588    color:neogene    text:[[Neogene]]  from: -2.588    till: 0   color:quaternary    text:[[Quaternary|Q.]]
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color:eocene bar:NAM1  from:-55.8    till:0 text:[[Atherina]]  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]]  color:miocene bar:NAM5 from:-11.608    till:0 text:[[Atherinopsis]]  color:pliocene bar:NAM6 from:-5.332    till:0 text:[[Chirostoma]]  color:pliocene bar:NAM7 from:-5.332    till:0 text:[[Colpichthys]]  color:pliocene bar:NAM8  from:-5.332    till:0 text:[[Menidia]]  color:pleistocene bar:NAM9  from:-2.588    till:0 text:[[Leuresthes]]
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bar:period  from: -65.5   till:  -55.8    color:paleocene  text:[[Paleocene]]  from: -55.8   till:  -33.9    color:eocene  text:[[Eocene]]   from: -33.9   till:  -23.03    color:oligocene  text:[[Oligocene]]              from: -23.03    till: -5.332    color:miocene    text:[[Miocene]]  from: -5.332    till: -2.588    color:pliocene    text:[[Plio.]]  from: -2.588    till: -0.0117   color:pleistocene    text:[[Pleist.]]  from: -0.0117    till: 0    color:holocene    text:[[Holocene|H.]]
bar:era  from: -65.5   till:  -23.03    color:paleogene  text:[[Paleogene]]           from: -23.03    till: -2.588    color:neogene    text:[[Neogene]]  from: -2.588    till: 0   color:quaternary    text:[[Quaternary|Q.]] References
