Akmonistion is an extinct genus of cartilaginous fish that lived in the Early Carboniferous.

The genus contains a single species, A. zangerli, discovered by Stan Wood in 1982.

[1] It is distinguished by an unusual enlarged formation of the dorsal fin, called a "spine-brush complex", of unknown function.

[2][3] The genus name is derived from the Ancient Greek “akmon” (“anvil”) + “istion” (“sail”) referring to the appearance of its first dorsal fin.

This article about a prehistoric cartilaginous fish is a stub.