Protacanthopterygidae

Protacanthopterygidae is a family of ray-finned fishes within the superorder Protacanthopterygii. Its taxonomic circumscription has varied among authorities, with some classifications treating Protacanthopterygidae as a distinct family and others placing its members within broader protacanthopterygian lineages or treating the group as a synonym or subfamily of a related family. This uncertain status reflects ongoing revisions in the systematics of Protacanthopterygii, aided by new morphological assessments and molecular data.

The group is defined by a relatively small number of genera and species, with a distribution that is primarily in northern temperate regions. Members are generally associated with freshwater environments, though some taxa may tolerate brackish conditions. Morphological characters used in its diagnosis typically concern fin arrangement and skeletal features that align with other protacanthopterygian fishes, helping to differentiate them within the broader radiation of the group.

Phylogenetic work continues to clarify the relationships of Protacanthopterygidae to other protacanthopterygians, including the salmoniforms and osmeriforms. While not a highly diverse or economically prominent family, Protacanthopterygidae contributes to the broader understanding of the evolutionary history and diversification of higher ray-finned fishes.

See also: Protacanthopterygii, Osmeriformes, Salmoniformes, Esociformes.