Characteristics of the order include the maxilla in the gape of the mouth, radii absent from the scales, and loss of the basisphenoid and orbitosphenoid bones. Almost all osmeriforms spawn in fresh water, but many are anadromous and found in temperate oceans worldwide.

The Argentinoidei are characterized by the presence of a crumenal organ, consisting of additional cartilage and gill rakers on the 5th ceratobranchial, while the Osmeroidea are notable for having their eggs surrounded by an adhesive membrane. Some classifications split the Argentinoidei genera Holtbyrnia, Maulsia, and Pellisolus out of the Platytroctidae family and into their own family called Searsiidae.

Classification

• Suborder Argentinoidei
• Superfamily Alepocephaloidea
• Alepocephalidae (slickheads)
• Leptochilichthyidae
• Platytroctidae
• Superfamily Argentinoidea
• Argentinidae (herring smelts)
• Bathylagidae (deep-sea smelts)
• Microstomatidae
• Opisthoproctidae (barreleyes)
• Suborder Osmeroidei
• Superfamily Galaxoidea
• Galaxiidae
• Lepidogalaxiidae (salamanderfishes)
• Retropinnidae (New Zealand smelts)
• Superfamily Osmeroidea
• Osmeridae (smelts)
• Plecoglossidae (ayu fishes)
• Salangidae (noodlefishes)

References

• J. S. Nelson, Fishes of the World