Aethalionopsis is an extinct genus of prehistoric freshwater bony fish from the Early Cretaceous (Barremian to early Aptian, with possible earlier or later occurrences) of western Europe.

[1] Formerly classified as a species of the elopiform Anaethalion, it is now known to be a relative of the modern milkfish (Chanos) in order Gonorhynchiformes.

[2][3][4][5] Only a single species is presently accepted, A. robustus from the famous Iguanodon dinosaur locality of the Sainte-Barbe Clays Formation in Bernissart, Belgium.

However, potential localities are also known from the Berriasian-Hauterivian of Sussex, England (classified in the genus Anaethalion as A. valdensis), and the Aptian-Albian of southern Italy (possibly an undescribed species).

However, more recent studies have only accepted and commented on A. robustus, with no mention of these other occurrences.