The Osmeriformes are an order of ray-finned fish that includes the true or freshwater smelts and allies, such as the noodlefishes; they are also collectively called osmeriforms. They belong to the teleost superorder Protacanthopterygii, which also includes pike and salmon, among others. The order's name means "smelt-shaped", from Osmerus (the type genus) + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek osmé (ὀσμή, "pungent smell") + Latin forma ("external form"), the former in reference to the characteristic aroma of the flesh of Osmerus.

In the classification used here, the order Osmeriformes contains two suborders, four families, some 17 genera, and about 52 species. The "marine" smelts and allies (e.g. the odd-looking barreleyes) were formerly included here as suborder Argentinoidei; they are now usually considered more distantly related than it was believed and treated as order Argentiniformes. When the marine smelts were included here, the subdivisions of the Osmeriformes were down-ranked by one. The galaxiids were also previously placed in this order, being treated as allied with the retropinnids, but are now known to represent their own, distinct order.

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