Gasteroclupea is a genus of prehistoric ellimmichthyiform fish that is distantly related to modern anchovies and herrings.

[1] It inhabited freshwater or estuarine habitats across South America during the Campanian and Maastrichtian stages of the Late Cretaceous period, and it briefly survived beyond the K-Pg boundary into the Danian stage of the Paleocene, making it among the few genera from its order to survive into the Cenozoic.

[3] Its taxonomic identity was long uncertain, often being placed as a clupeid or an indeterminate clupeomorph, but more recent studies have placed it with the Ellimmichthyiformes.

Its closest relative has been found to be Sorbinichthys, another unusual ellimmichthyiform from marine deposits in Lebanon,[3][4][5] though some studies have been inconclusive about this.

As with modern freshwater hatchetfish, its upturned mouth may have been an adaptation to a lifestyle of feeding on fallen insects on the water's surface.