Osmeriformes

(Salangidae) are unusual osmeriforms that are commonly harvested Osmeriformes are small to mid-sized slender fish. Their maxilla is usually included in the mouth's gape, and most of them have an adipose fin as is often found in the Protacanthopterygii. Their [pterosphenoid] usually has a ventral flange, and the vomer has a short posterior shaft. They have reduced or even missing articular and mesopterygoid teeth, and the basisphenoid and orbitosphenoid bones are entirely absent. Their scales lack radii. Despite the term "freshwater smelts", the members of the Osmeriformes are generally marine, amphidromous or anadromous migrants. Even the sedentary freshwater species in this family are usually tolerant of considerable changes in salinity. Almost all osmeriforms spawn in fresh water, thus the marine species are generally anadromous. They are found in temperate oceans worldwide and in temperate freshwater of the Holarctic and around the South Pacific region; only a handful of species occur in tropical waters. The eggs are surrounded by an adhesive membrane. ==Systematics==

(Retropinna retropinna), one of the few species in the Retropinnidae With the Argentiniformes, Alepocephaliformes, Galaxiiformes, and Lepidogalaxiiformes separated as distinct orders, the remaining Osmeriformes appear to be a monophyletic group. As protacanthopterygians, they are known to be related to the Salmoniformes (pikes and salmon). However, more recent studies incorporating anatomical and DNA sequence data suggest that their closest relatives are the deep-sea Stomiiformes. The classification of the Osmeriformes as approached here is: • Family ?†Spaniodontidae Jordan, 1905 (Late Cretaceous (Santonian) of Lebanon) • Suborder Retropinnoidei • Family †Ferruaspidae McCurry et al., 2025 (Late Miocene of New South Wales, Australia) • Family Retropinnidae Gill, 1862 - Australian-New Zealand smelts and graylings (3 genera) • Suborder Osmeroidei • Genus †Speirsaenigma Wilson & Williams, 1991 (Late Paleocene of Alberta, Canada) • Family Osmeridae Regan, 1913 - freshwater smelts, typical smelts (6 genera) • Family Plecoglossidae Bleeker, 1859 - ayu (1 genus) • Family Salangidae Bleeker, 1859 - noodlefishes, "icefish" (7 genera) -aged Spaniodon potentially represents an early osmeriform In 2025, a new, extinct family of freshwater Southern Hemisphere smelt, the Ferruaspidae, was identified from the Miocene-aged McGraths Flat fossil site of Australia. The families Galaxiidae and Lepidogalaxiidae were at one time placed together with Retropinnidae in the sub order Galaxoidei, however with new molecular studies they have been elevated to the ordinal level. ==Timeline of genera==

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